Julia Child’s mustard coating recipe for the most flavorful leg of lamb ever, and it’s so easy to make. Use it on chicken and beef, too!
Gigot a la Moutarde
Julia Child included her recipe for mustard-coated roast leg of lamb in her famous cookbook Mastering the Art of French Cooking which was first published in 1961. The coating is an easy emulsion of mustard, fresh rosemary, garlic, olive oil, and soy sauce. She grinds it up with a mortar and pestle and drizzles in the oil while whisking to create a sauce. She then smears it all over a leg of lamb.
But you don’t have to save this luxuriously thick mustard coating for a leg of lamb, it can be used on all different cuts of lamb, as well as on chicken, roast beef, beef tenderloin, or even fish, so it’s a great one to have under your belt. And it takes just seconds to make!
can I one-up Julia?
I think I can, with fresh rosemary, a little lemon, and my immersion blender 🙂
what you’ll need for Julia Child’s mustard coating
- Dijon mustard
- Julia uses a smooth Dijon mustard. I used half smooth and half whole grain Dijon because I love the added texture.
- Julia uses one clove, I added two.
- olive oil
- the good stuff: extra virgin.
- Julia uses dried rosemary, I use fresh, and it makes a HUGE difference.
- soy sauce
- the one non-French ingredient in this coating!
- lemon juice
- Julia does not use this, but it adds the perfect touch of acidity.
how to blend Julia’s mustard coating with your immersion blender
This is a quick and easier method to replace the old drizzle and whisk method. It produces a faster, thicker result. Don’t have an immersion blender? For heaven’s sake, get one!! (This is the one I have.)
- Put all the ingredients into a jar that just fits the head of your immersion blender. If you use a bowl, or a larger jar, the blender won’t be able to generate as much velocity and you may have trouble getting that gorgeously thick emulsion.
- Place the head of the blender on the bottom of the jar and blend! Wiggle the head around to get everything nice and thick and silky. It takes about 30 seconds.
You’re essentially making a rosemary mustard mayonnaise! This is the same method I use for my other 30-second sauces:
make mustard lamb coating ahead
Your coating can be kept in the refrigerator for up to a day ahead of time. I like to coat my lamb and then let it marinate in the fridge overnight anyway.
how to use Julia Child’s mustard coating for lamb
Julia uses this coating for a semi-boneless leg of lamb. She generously coats the entire lamb, both sides, with the mustard sauce. The sauce is nice and thick, like mayonnaise, so it stays put and doesn’t drip off the meat.
You can roast your meat right away, but a better idea is to refrigerate it for at least 2 hours, or overnight to let the flavors penetrate.
Roasting your leg of lamb
Here’s a general guideline for cooking a bone-in leg of lamb at 350°F (177°C) but be aware, these times work for lamb that has been taken out of the refrigerator at least 30 minutes or more ahead of time so it’s not cold:
- For rare: Cook at 350°F (177°C) for 18-20 minutes per pound, or until the internal temperature of the lamb reaches 135°F (57°C).
- For medium-rare: Cook at 350°F (177°C) for 20-22 minutes per pound, or until the internal temperature of the lamb reaches 145°F (63°C).
- For medium: Cook at 350°F (177°C) for 22-25 minutes per pound, or until the internal temperature of the lamb reaches 160°F (71°C).
- For well-done: Cook at 350°F (177°C) for 25-30 minutes per pound, or until the internal temperature of the lamb reaches 170°F (77°C).
Be sure to use a meat thermometer to check the temperature of the lamb to ensure it is cooked to your preferred level of doneness. Let the lamb rest for 10-15 minutes before carving to allow the juices to redistribute.
other sauces, condiments, and dressings to make at home
- Creamy Homemade Horseradish Sauce (from scratch!)
- Japanese Carrot Ginger Dressing
- 3 green sauces you should know how to make!
- Red Enchilada Sauce
- Thai Peanut Sauce Recipe
- Sweet Chili Sauce Recipe
- Buttermilk Blue Cheese Dressing
- Raspberry Poppy Seed Dressing
Julia Child’s Mustard Coating for Lamb
- an immersion blender
- jar that fits the head of the blender
- Put everything into a jar that just fits the head of your immersion blender.
- Place the head of the blender at the bottom of the jar and turn it on. Wiggle the head a bit to get everything nice and thick.
- Use immediately or keep your mustard coating in an airtight container in the refrigerator until needed.
to use on a leg of lamb
- Trim excess fat from your leg of lamb. Spread the mustard coating thickly over the entire leg, on all sides. Cover with plastic and refrigerate for at least 2 hours, or overnight, to allow the flavors to penetrate the meat.
- Roast the lamb at 350°F (177°C) for 20-22 minutes per pound, or until the internal temperature of the lamb reaches 145°F (63°C) for medium-rare or 160°F (71°C) for medium.
- Remove the lamb from the oven and let it rest for 10-15 minutes before carving to allow the juices to redistribute.