Mustard and Herb Roasted Leg of Lamb

Close up of medium rare roasted boneless leg of lamb.

5 from 7 votes

Mustard and Herb Roasted Leg of Lamb

Mustard and herb rubbed and roasted leg of lamb, Gigot à la Moutarde from Julia Child. Adding lemon, onion and fresh herbs to the roasting pan yields a delicious pan gravy.

Prep Time2

Cook Time2

Total Time4

Course: Main Course

Cuisine: French

Servings: servings

Calories: 319kcal

Author: Kelly Wildenhaus

Ingredients

1 5-pound boneless leg of lamb
½ cup Dijon mustard
2 tablespoon soy sauce
3 cloves garlic, minced ~ I used a garlic press
1 teaspoon dried thyme
1 teaspoon dried rosemary
¼ teaspoon ground ginger
2 tablespoon olive oil
½ small onion, roughly sliced
½ lemon, sliced
Several sprigs fresh rosemary and thyme
2-4 cups chicken stock
2 tablespoon flour
2-4 tablespoon water
½ cup white wine

Instructions

Mix mustard, soy sauce, garlic, rosemary, thyme and ginger together in a bowl. In a steady, slow stream, whisk in olive oil until well-combined and emulsified, like a mayonnaise-like cream.
Paint the lamb all over with the mustard mixture and set it on rack, fat side up, in roasting pan. Let sit at room temperature for 2 hours before roasting.
Preheat oven to 425º. Scatter chopped onion, lemon slices and fresh herbs in bottom of pan, under the rack. Roast for 30 minutes and then turn oven temperature down to 350º. Roast until desired doneness, 135º for medium-rare, 145º for medium; about 1½ hours more. Add about 2 cups chicken stock to the pan after 1 hour and add some more as needed after about another ½ hour. Pull the roast out of oven 5 degrees shy of goal temperature, transfer to cutting board or platter, tent with foil and let rest 20 to 30 minutes.
Meanwhile, make the gravy. Strain and de-fat pan juices and drippings into large measuring cup and set aside. If necessary, add more chicken stock to make at least 2 cups. Make a slurry by mixing flour and water until a thick liquid, but not a paste. Place roasting pan on stove and turn 1 to 2 burners on high. Pour wine into pan and deglaze, scraping up any browned bits, and reduce by half. Pour reserved pan juices into pan and whisk to combine. Slowly pour slurry into pan while whisking constantly until pan sauce starts to thicken; cook at a steady simmer until thickened and flour taste is cooked off, about 5 to 10 minutes. Taste for salt and pepper.
Snip netting/string on roast and carefully lift out roast, removing the string. Slice lamb and serve with gravy on the side.

Notes

When using dried herbs, I like to crush/rub them in my hand to release oils and flavor.
You certainly can marinate the lamb longer for more flavor, for several hours, or even overnight, in the refrigerator. Pull out 2 hours before roasting to bring to room temp.
Cooking time will vary depending on the size of roast and your ideal doneness. My 5-pound roast took 2 hours total for medium-rare and I pulled it out when it registered 130º on an instant read thermometer.
I start adding chicken stock to the pan after about an hour and use my judgement, anywhere from 2 to 4 cups total during the last hour of cooking to ensure enough pan juices/drippings for gravy.
Removing the netting/string can be messy and feel like you're destroying the beautiful crust. Do your best, you can easily press the crust back down as you're removing the string. Removing the netting before you cook is not a good idea unless you are stuffing the roast, otherwise you risk it coming apart and not cooking evenly.

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