Leg of Lamb with Rosemary Recipe in Dutch Oven

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This is a quick leg of lamb with rosemary recipe with just 6 ingredients. I make it in my Dutch oven. I season it with rosemary, garlic, onions, olive oil, and Dijon mustard. It’s always savory and juicy. I wanted to share this easy leg of lamb recipe because it is delicious and easy to make.

Lamb is expensive. The last thing you want is for it to be dry or overcooked. While the fat helps ensure it stays tender (cook it fat side up), I prefer slow-cooking lamb in a Dutch oven rather than roasting it in a casserole dish or baking tray.

I have had success roasting lamb on a baking tray and covering it with foil but when I make it in a Dutch oven, I put it in the oven, and take it out, and that’s it… no foil covering is needed.

Keep reading to learn how to make leg of lamb with rosemary. It takes less than 10 minutes of prep time.

Boneless Leg of Lamb with Rosemary

If you don’t have a Dutch oven, you can make lamb in a crock pot, on a baking sheet, or in a casserole dish. The difference will be the oven temperature and how long it cooks. These instructions are for making lamb in a Dutch oven. When covered, you can bake the lamb at 325 degrees F instead of roasting at 400 degrees F on a tray or dish.

Whichever way you make lamb, the rule of thumb is to cook it for 20 minutes for every pound of lamb.

 It’s important to note this rosemary lamb recipe is forgiving. If you add more or less of an ingredient, it will still taste great. Be sure to have enough to cover all sides of the lamb. If you use fresh herbs, feel free to be generous with tossing them in.

cooked leg of lamb with rosemary in Dutch oven
Cooked leg of lamb with rosemary in Dutch oven

This is a no salt lamb recipe but add salt or pepper as you wish. You can use these ingredients whether you are making a boneless leg of lamb or bone-in leg.

Ingredients

  • Leg of lamb
  • 3 – 4 tablespoons olive oil
  • 3 – 4 tablespoons Dijon mustard
  • 2 white or yellow onions
  • 1 – 2 tablespoon garlic powder
  • 2 tablespoons dried rosemary or 5 – 6 sprigs fresh rosemary (however much you have)
  • 1 tablespoon dried thyme or 5 – 6 sprigs of fresh thyme

Equipment 

  • Cutting board and knife
  • Medium bowl
  • Measuring spoons and cups – Optional; you can estimate as you go if you prefer
  • Dutch oven

How to Make Leg of Lamb in Dutch Oven

  1. Preheat oven to 325ºF; set to roast or bake.
  2. Use a teaspoon of olive oil to coat the bottom of Dutch oven or pot so it’s lightly covered.
  3. Wash and chop onions; put in pot.
  4. Take lamb out of packaging, rinse, and place in Dutch oven on top of the onions.
  5. In a medium bowl, combine remaining olive oil, Dijon mustard, garlic powder, rosemary, and thyme, and stir.
  6. Apply mixture to lamb on all sides while it’s in the Dutch oven.
  7. Place the lamb fat side up and cover with lid.
  8. Set in preheated oven for 20 minutes per pound of lamb.
  9. When timer goes off, remove from oven and set on stovetop.
  10. Check for doneness in the center and in the thickest part of the lamb with meat thermometer. It should be a minimum of 145ºF for medium. If not, cover, and return to oven for 5 – 10 minutes and check again.
  11. Let rest for 10 – 15 minutes on stovetop, then serve directly out of the Dutch oven.
Roast lamb cooking time
Roast lamb cooking time is 20 minutes per pound; it should be a minimum internal temperature of 145ºF

Tips

  • I like seasoning the leg directly in the Dutch oven so the extra goes on the onions and isn’t wasted. 
  • If you aren’t ready to serve the lamb when it’s out of the oven, you can leave it covered in the Dutch oven for up to 2 hours to serve.
  • If you don’t want to bake or roast the lamb, other options are to grill it or to place the leg of lamb on a rotisserie.

Ingredient Options

Olive oil vs other oil: I buy Kirkland Signature Organic Pure Extra Virgin Olive Oil from Costco. It’s a quality, good-tasting olive oil. I like using olive oil when cooking lamb and other meats for the flavor it adds. However, if you don’t have olive oil, you can use avocado oil or vegetable oil.

Garlic powder vs garlic cloves: If you prefer using garlic cloves instead of garlic powder, you can stuff garlic cloves into the lamb meat (make slits in the lamb). Another option is to chop the garlic — or use a garlic press — and sauté it on the stovetop in some olive oil before adding it to the lamb. Or do both.

Onions vs onion powder: I like adding chopped onions to cook with lamb and other meat dishes. It looks nice with the lamb, is more to eat (helps to stretch the meal a bit), and gives it additional flavor and nutrition. 

Fresh herbs vs dried herbs: If you grow fresh herbs, such as rosemary and thyme, use them liberally in this boneless leg of lamb with rosemary recipe. If you buy packages of fresh herbs at the grocery store, feel free to use it all in this recipe (or use or freeze the remaining herbs; they are expensive — you don’t want them to go to waste). Otherwise, you can use dried herbs. 

what to serve with lamb
Wondering what to serve with lamb? Lamb goes well with potatoes, rice, carrots, turnips, rolls, and salad

What to Serve with Roasted Lamb with Rosemary

Lamb goes well with potatoes, rice, and vegetable dishes. I’ve served lamb with garlic roasted turnips and turnip greens (from my garden!) and honey-glazed carrots. It also goes well with au gratin potatoes or scalloped potatoes. Serve with some rolls and a salad. It’s easy to serve lamb because it’s the star of the plate. Anything else will complement it. I enjoy serving it for our Sunday family dinners.

Storing

If you make the lamb in advance and aren’t serving it right away, after about 30 – 60 minutes (enough to cool it a bit), store the rosemary lamb covered in the Dutch oven in the refrigerator for 3 – 5 days.

You can store leftovers in the Dutch oven or in a covered container. You can also freeze cooked and cooled lamb in freezer bags. Thaw overnight in the fridge before reheating.

How to Cook Leg of Lamb

My favorite way to cook a boneless lamb roast is to set it in a Dutch oven and set it in the oven. I set my oven to the Bake setting at 325º F. I cook for 20 minutes for every pound for medium doneness. If you don’t have a Dutch oven and make lamb in a roasting dish, you can set the oven to Roast at 400º F

Rosemary garlic lamb
Rosemary garlic lamb is easy to make in a Dutch oven

Lamb Internal Temperature

It’s important to cook lamb to a minimum internal temperature of 145° F / 62.8° C. Use a food thermometer before removing meat from the heat source. It’s also important to let the lamb rest for a minimum of 3 minutes before cutting or eating.

Depending on the manner in which you cook it (bake on lower temperature or roast on higher temperature) and what you cook it in, the times can vary. In general, you should cook boneless leg of lamb for 20 minutes per pound approximately.

lamb roast with rosemary
Lamb roast with rosemary, garlic, thyme, onions, and Dijon 

Lamb Cooking Times

Using a roasting dish in the oven: Set oven on 400 degrees F. Roast for 20 minutes for every pound of lamb. Example baking times:

  • Roasting 5 pounds of lamb at 400ºF = 1 hour, 40 minutes
  • Roasting 6 pounds of lamb at 400ºF = 2 hours

Please follow the directions on the package. Use a meat thermometer and set it in the middle of the lamb. Lamb should have an internal temperature of 145ºF (62.8°C) to be safe to eat. 

Where to Buy Leg of Lamb

Buying lamb is a treat in our house because of the price. I found a very good quality lamb at Costco with their Kirkland Signature brand. The label describes it as: Lamb Leg Boneless Roast Australia.

I freeze it until I’m ready to use it. To defrost, I set it in the refrigerator for 20 – 24 hours. I’ve had success setting it in the oven and roasting lamb on a baking tray I line with foil as well as in a casserole dish. Using the crock pot is another way to make lamb. I like it in the crockpot because it remains tender.

My favorite way to make leg of lamb with rosemary is in my Dutch oven. Being covered, it helps to regulate the temperature and keeps all the tenderness and flavor.

Roast Lamb Recipe

Whether you raise lamb on your homestead or buy already-processed lamb from a farmer, butcher, grocery store, or Costco or Sam’s Club, cooked properly, lamb is a savory red meat. In the United States, lamb isn’t as popular as beef, nor is it as common as pork or chicken. However, it’s very easy to make.

I like using Dijon mustard when making lamb. Combined with the olive oil and herbs, you won’t miss extra salt.

Like many recipes that use herbs and spices, this recipe is forgiving. If you don’t have something, you can make a substitution. If you add more or less of an herb or spice, it’s fine and will still come out great.

I have lots of rosemary growing in pots on my property, so I use fresh rosemary in abundance. However, you can use dried rosemary as well. The same for thyme, you can use fresh or dried.

Herbs are so easy to grow. Learn how to grow rosemary so you can add it to lamb, beef, chicken, potatoes, and more. 

You can also try a variety of different spices and herbs… experiment! Please leave a comment with what your favorite way to prepare lamb is. Do you like the combination of rosemary, thyme, garlic, olive oil, and Dijon? Let me know.

Leg of lamb with rosemary
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Leg of Lamb with Rosemary

This fast and easy leg of lamb with rosemary, thyme, Dijon, and garlic uses only 6 ingredients. With a few minutes of prep, set it in the Dutch oven for a special dinner or a busy weeknight. Cook for 20 minutes per pound.
Course Main Course
Cuisine American
Keyword easy leg of lamb, leg of lamb, leg of lamb recipe, leg of lamb with rosemary, leg of lamb with rosemary recipe
Prep Time 5 minutes
Cook Time 1 hour 40 minutes
Resting 10 minutes
Servings 5

Ingredients

  • Leg of lamb
  • 3 - 4 tablespoons olive oil
  • 3 - 4 tablespoons Dijon mustard
  • 2 white or yellow onions
  • 1 - 2 tablespoon garlic powder
  • 2 tablespoons dried rosemary or 5 - 6 sprigs fresh rosemary however much you have
  • 1 tablespoon dried thyme or 5 - 6 sprigs of fresh thyme

Instructions

  • Preheat oven to 325ºF; set to roast or bake.
  • Use a teaspoon of olive oil to coat the bottom of Dutch oven or pot, covering lightly.
  • Wash and chop onions; put in Dutch oven.
  • Take lamb out of packaging, rinse, and place in pot on top of onions.
  • In a medium bowl, combine remaining olive oil, Dijon mustard, garlic powder, rosemary, thyme, and stir.
  • Apply mixture to lamb on all sides while it's in the Dutch oven.
  • Place the lamb fat side up; cover with lid.
  • Set in preheated oven for 20 minutes per pound of lamb.
  • When timer goes off, remove from oven and set on stovetop.
  • Check for doneness in the center and in the thickest part of the lamb with meat thermometer. It should be a minimum of 145ºF for medium. If not, cover, and return to oven for 5 - 10 minutes and check again.
  • Let rest for 5 - 10 minutes on stovetop. Serve directly out of the Dutch oven.

Notes

  • Lamb should be cooked to an internal temperature of 145ºF. Use a food thermometer in the thickest part of the lamb.
  • Save time by seasoning the lamb leg directly in the Dutch oven.
  • Let the lamb rest in the Dutch oven for 5 - 10 minutes before cutting and serving.
  • Use this recipe to make boneless lamb or bone-in lamb.