Our Low FODMAP Slow Roasted Boneless Leg of Lamb features flavors of garlic (yes, garlic; more on that later) lemon and anchovy and is quite simple to make. Slow roasting uses the reverse sear technique, which means we roast the lamb in a low temperature oven for a couple of hours, and then finish it off searing in a very high heat oven. You will be rewarded with an evenly roasted leg of lamb, done to your liking. Note that we suggest an overnight marination in the refrigerator prior to roasting, so plan accordingly. Also make sure you have room in your refrigerator for a roasting pan, and an instant read thermometer on hand.
A fantastic dish for Easter or Passover – or anytime you want to feed a crowd. No one will think this is special “diet” food. Fantastic with our Low FODMAP Scalloped Potatoes alongside our Low FODMAP Honey Lemon Pan Roasted Carrots.
This dish was inspired by one created by J. Kenji Lopez-Alt, from SeriousEats.The original was high FODMAP, so we took it through our FODMAP IT!™ process.
Frequently Asked Questions
What Is A Butterflied Leg of Lamb?
You do need boneless leg of lamb to make this dish. This allows you to unroll it and open it up, which is simply what a butterflied leg of lamb is. Once the leg of lamb is open in front of you, spread our flavorful garlic/lemon/anchovy seasoning mixture inside it. Then, the leg of lamb is rolled back up, tied firmly into shape with butcher twine and slathered with more seasoning mixture on the outside.
What Is “Low FODMAP Garlic Powder”?
PLEASE READ THIS SECTION! Conventional garlic powder (and onion powder, for that matter) is high FODMAP; it is dried and granulated garlic. There are low FODMAP garlic powders on the market that you can use, even during Elimination. FreeFod Garlic Replacer is the first product that came to our attention. These products are made from maltodextrin and natural flavoring, and although the flavoring is natural and both FreeFod and Fodmazing brands state it is derived from garlic, the fact that the FreeFod product has been lab tested and certified low FODMAP by FODMAP Friendly once again shows us that this diet is not “no FODMAP”, but low FODMAP. There are many food items, such as Worcestershire sauce and conventional ketchup, that contain garlic and because the serving sizes are small, they are considered low FODMAP.
We like these low FODMAP garlic powders very much. They allow for an easy way of adding garlic flavor to our dishes and we recommend you add them to your herb and spice collection.
Is Leek Bulb Low FODMAP?
Monash University has now lab re-tested leeks and leek bulbs and reports that 2 Australian tablespoons, or 14 g, of leek bulb are low FODMAP. This opens up a world of oniony flavor for us FODMAPers.
Do I Have To Use Anchovy?
We know that anchovies are polarizing. It seems as though folks love them, or really do not. I invite you to think of them as savory flavor enhancers, as opposed to being “fishy”. In fact, they do have umami complexity and add immensely to this dish. We highly suggest you use them the first time you make this recipe. If you didn’t know the anchovies were in there, we doubt you’d be able to tell. The anti-anchovy folks in the house loved this dish!
Can I Use Other Flavorings?
Once you get the hang of creating a seasoning mixture, slathering the meat inside and out and tying it up, you could expand your options. The key when tweaking any of our recipes is that you must recognize that you have to recalculate the FODMAP load if you make any changes. You have to have a good understanding of the diet and of stacking.
For instance, how about garlic flavor (powder and oil), chopped scallion greens, cumin and lemon? Or, olive oil, garlic flavors, lemon and rosemary would be fantastic. If you are comfortable in the kitchen, and have a strong understanding of the diet, get creative. Let us know what you come up with!
How Do I Roll A Boneless Leg Of Lamb?
You can see in our images below that the unrolled, open, butterflied leg of lamb is not a very even shape. Each one will be a tad different. We found a video for you that shows the technique of rolling and tying with butcher twine. The thing is, the more evenly the lamb is rolled and tied, the more evenly it will roast, but we know some pieces of meat will be more difficult to form into a nice, even shape than others. Don’t sweat it too much. Just get it tied and it will work! Promise.
Can I Use A Different Size Leg Of Lamb?
Yes, just figure on about 15 to 20 minutes per pound as your guide to yield a medium-rare result.
What Is Butcher Twine?
Butcher twine is white cotton twine that can withstand the high heat of the oven. It is most often used to help truss a bird (think Thanksgiving turkey and even weeknight whole roast chicken) and also when roasting meats, from pork and beef, to this lamb dish. It is inexpensive and we think it is a must to have in your pantry.
How To Make Our Low FODMAP Slow Roasted Leg of Lamb
Unroll the boneless leg of lamb in front of you on your work surface.
Remove any excess fat pockets and discard. Evenly sprinkle with your low FODMAP garlic powder; set aside.
The garlic flavor will permeate the meat as you work on the marinade.
Heat oil over low-medium heat in a small saucepan until shimmering. Add the minced leek bulb, scallion greens, anchovies, lemon zest, rosemary, and red pepper flakes.
Cook, stirring often, for about five minutes or until the leeks and scallions have softened. Make sure the anchovies are mashed and mixed into the rest of the mixture; you can do this with the back of a spoon.
Set aside to cool.
Season the inside of the butterflied lamb well with salt and pepper. Spread about half of the cooled lemon anchovy mixture over the butterflied lamb; just schmear it on with fingers, a silicone spatula or use the back of a spoon.
Now it is time to roll up the lamb and tie it. Depending on its shape, you might have to tuck in some ends here and there, but you are trying to create a fairly smooth, plump oval. Like a football shape with rounded ends. Use butcher twine to tie it at even intervals to hold it together.
Line a roasting pan with foil and place a flat rack on top. Place the lamb on top of the rack (I like fat cap down). Season exterior of lamb, all over, with salt and pepper. Slather the lamb all over with the reserved marinade, paying most attention to the areas of flesh, as opposed to fat.
Place uncovered in the refrigerator overnight.
Place rack in lower third of oven. Preheat oven to 275°F (135°C). Place lamb in oven and roast at this low temperature for about 2 ¼ to 2 ¾ hours or until the internal temperature reaches 125° F to 130°F (52°C to 55°C). This allows the meat to rise about 5° in temperature upon resting, yielding a lovely medium-rare roast. Adjust your timing as desired. Use 15 to 20 minutes per pound as your guide. Let rest for 30 to 40 minutes, while you prepare your side dishes.
Crank the oven up to 500°F (260°C) and place lamb back in oven to sear, for about 8 to 10 minutes. Just let it get a nice crackly crust, here and there.
Remove the twine (I use shears) and you are ready to carve and serve.
More Lamb Recipes
Lamb lover? We’ve got the low FODMAP recipes you are looking for!
- Garlic & Herb Roast Leg of Lamb
- Gyros, using leftovers
- Lamb Curry, using leftovers
- Lamb Burgers with Tzatziki Sauce
- Lamb Burgers with Tahini
- Irish Lamb Stew
- Moroccan Lamb Shanks with Pomegranate and Mint
- Grilled Butterfly Leg of Lamb
- Yogurt Spiced Lamb Chops
FODMAP Information
All recipes are based upon Monash University & FODMAP Friendly science at time of initial publication.
- Low FODMAP Garlic Powder: There are a couple of low FODMAP garlic powders on the market, made from maltodextrin and garlic flavor, that you can use like traditional garlic powder. FreeFod Garlic Replacer is certified low FODMAP by FODMAP Friendly. From what we can tell, Fodmazing Garlic Replacer Substitute contains the same ingredients, and we use both.
- Garlic-Infused Oil: Make your own Garlic-Infused Oil or buy a commercial equivalent for the easiest way to add garlic flavor to your food. Fructans in garlic are not oil-soluble, so garlic-infused oil is low FODMAP.
- Leeks: The green parts of leeks are low FODMAP as determined by Monash University lab testing and can be used to add onion flavor to your low FODMAP cooking. Monash also states that 2 Australian tablespoons, or 14 g, of leek bulb are low FODMAP.
- Scallions: The green parts of scallions are low FODMAP as determined by Monash University lab testing and can be used to add onion flavor to your low FODMAP cooking.
Please always refer to the Monash University & FODMAP Friendly smartphone apps for the most up-to-date lab tested information. Foods will be retested from time to time; in the case of raw ingredients, such as fruits and vegetables, results may vary. All lab tested results are valid and represent a snapshot in time. As always, your tolerance is what counts; please eat accordingly. The ultimate goal of the low FODMAP diet is to eat as broadly as possible, without triggering symptoms, for the healthiest microbiome.
Low FODMAP Slow Roasted Boneless Leg of Lamb
Our Low FODMAP Slow Roasted Boneless Leg of Lamb features flavors of garlic (yes, garlic; more on that later) lemon and anchovy and is quite simple to make. Slow roasting uses the reverse sear technique, which means we roast the lamb in a low temperature oven for a couple of hours, and then finish it off searing in a very high heat oven. You will be rewarded with an evenly roasted leg of lamb, done to your liking.
Ingredients:
- 7- pound to 8-pound (3.2 kg to 3.6 kg) boneless leg of lamb
- 1 teaspoon low FODMAP garlic powder, such as FreeFod or Fodmazing
- 2 tablespoons low FODMAP Garlic Infused Oil, made with olive oil, or purchased equivalent
- ½ cup (56 g) finely minced leek bulb
- ½ cup (32 g) finely minced scallions, green parts only
- 6 flat anchovy fillets, packed and oil, chopped
- 1 tablespoon finely minced lemon zest, preferably made with a rasp-style zester
- 1 tablespoon minced fresh rosemary
- ½ teaspoon red pepper flakes
- 2 tablespoons kosher salt
- ¾ teaspoon freshly ground black pepper
- Butcher twine
Preparation:
-
Unroll the boneless leg of lamb in front of you on your work surface. Remove any excess fat pockets and discard. Evenly sprinkle with your low FODMAP garlic powder; set aside. The garlic flavor will permeate the meat as you work on the marinade.
-
Heat oil over low-medium heat in a small saucepan until shimmering. Add the minced leek bulb, scallion greens, anchovies, lemon zest, rosemary, and red pepper flakes and cook, stirring often, for about five minutes or until the leeks and scallions have softened. Make sure the anchovies are mashed and mixed into the rest of the mixture; you can do this with the back of a spoon. Set aside to cool.
-
Season the inside of the butterflied lamb well with salt and pepper. Spread about half of the cooled lemon anchovy mixture over the butterflied lamb; just schmear it on with fingers, a silicone spatula or use the back of a spoon. Now it is time to roll up the lamb and tie it. Depending on its shape, you might have to tuck in some ends here and there, but you are trying to create a fairly smooth, plump oval. Like a football shape with rounded ends. Use butcher twine to tie it at even intervals to hold it together.
-
Line a roasting pan with foil and place a flat rack on top. Place the lamb on top of the rack (I like fat cap down). Season exterior of lamb, all over, with salt and pepper. Slather the lamb all over with the reserved marinade, paying most attention to the areas of flesh, as opposed to fat. Place uncovered in the refrigerator overnight.
-
Place rack in lower third of oven. Preheat oven to 275°F (135°C). Place lamb in oven and roast at this low temperature for about 2 ¼ to 2 ¾ hours or until the internal temperature reaches 125° F to 130°F (52°C to 55°C). This allows the meat to rise about 5° in temperature upon resting, yielding a lovely medium-rare roast. Adjust your timing as desired. Use 15 to 20 minutes per pound as your guide. Let rest for 30 to 40 minutes, while you prepare your side dishes.
-
Crank the oven up to 500°F (260°C) and place lamb back in oven to sear, for about 8 to 10 minutes. Just let it get a nice crackly crust, here and there. Remove the twine (I use shears) and you are ready to carve and serve.
Notes:
FODMAP Information
Our recipes are based on Monash University and FODMAP Friendly science.
• Low FODMAP Garlic Powder: There are a couple of low FODMAP garlic powders on the market, made from maltodextrin and garlic flavor, that you can use like traditional garlic powder. FreeFod Garlic Replacer is certified low FODMAP by FODMAP Friendly. From what we can tell, Fodmazing Garlic Replacer Substitute contains the same ingredients, and we use both.
• Garlic-Infused Oil: Make your own Garlic-Infused Oil or buy a commercial equivalent for the easiest way to add garlic flavor to your food. Fructans in garlic are not oil-soluble, so garlic-infused oil is low FODMAP.
• Leeks: The green parts of leeks are low FODMAP as determined by Monash University lab testing and can be used to add onion flavor to your low FODMAP cooking. Monash also states that 2 Australian tablespoons, or 14 g, of leek bulb are low FODMAP.
• Scallions: The green parts of scallions are low FODMAP as determined by Monash University lab testing and can be used to add onion flavor to your low FODMAP cooking.
Please always refer to the Monash University & FODMAP Friendly smartphone apps for the most up-to-date lab tested information. Foods will be retested from time to time; in the case of raw ingredients, such as fruits and vegetables, results may vary. All lab tested results are valid and represent a snapshot in time. As always, your tolerance is what counts; please eat accordingly. The ultimate goal of the low FODMAP diet is to eat as broadly as possible, without triggering symptoms, for the healthiest microbiome.
Nutrition
All nutritional information is based on third-party calculations and should be considered estimates. Actual nutritional content will vary with brands used, measuring methods, portion sizes and more. For a more detailed explanation, please read our article Understanding The Nutrition Panel Within Our Recipes.
Was a little dubious about the temperature and the time calculated for my roast (1.9 kg). However, followed your instructions and timing guide and everything turned out perfect.
I did however, omitted the foil from the baking pan and poured just a little water (half cup?) instead. It was lovely and brown at the end of the first bake. I then added a bit more to prevent the drippings from actually burning. When baking is complete, I then transferred the roast to a plate and proceeded to make gravy from the drippings with a little salt and low FODMAP thickener.
Shall certainly be making this again as hubby loves his Sunday lamb roast. Thanks for a lovely and delicious Sunday! ❤️
Thank you for writing! So glad to hear that this worked and the family enjoyed it. Hope you had leftovers, because you can get creative!