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Juicy Mustard Lamb Roast

Featured in Dinner Solutions You'll Love.

Slather mustard-herb mix on lamb, roast hot to start, finish at low heat, rest it, slice, and pair with a pan gravy.
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Rose
Updated on Thu, 20 Mar 2025 17:13:56 GMT
Juicy Lamb with Mustard and Herbs Pin it
Juicy Lamb with Mustard and Herbs | tastybysophie.com

Last Easter, I whipped up this mustard-coated lamb roast that blew everyone away. My mother-in-law even asked for my recipe – basically the cooking equivalent of hitting the jackpot! The herby mustard layer forms this amazing seal that locks in all the juices, turning even the biggest lamb doubters into fans asking for more.

My lamb-hating brother shocked everyone by gobbling up three servings and then casually hinted that I should "maybe cook this again" for his next visit.

Essential Ingredients

  • Boneless leg of lamb: Go for lamb from Australia or New Zealand for a gentler taste that'll win over hesitant eaters.
  • Dijon mustard: Forms the zingy foundation for your herb coating. Try whole grain if you want some extra bite.
  • Fresh herbs: Don't skimp on fresh rosemary and thyme – they're lamb's best friends for good reason.
  • Garlic: Be generous here – its bold kick pairs wonderfully with lamb.
  • Soy sauce: A tiny splash adds richness without any Asian flavor notes.
  • White wine: Softens the meat and builds that fantastic sauce later.
  • Good quality olive oil: Helps everything stick together and adds some luxury.
Tangy Herb-Crusted Mustard Lamb Roast with Savory Drippings Pin it
Tangy Herb-Crusted Mustard Lamb Roast with Savory Drippings | tastybysophie.com

My Cooking Method

Getting Started

I always thoroughly dry the lamb with paper towels before adding any mustard mix. This trick helps everything stick properly and pumps up the flavor. Letting the meat sit out until it reaches room temp isn't optional – it's crucial for even cooking throughout.

Mustard Coating

Slather that mustard mix all over your lamb, making sure it gets into every little crevice. I've found fingers work way better than tools for this job. Don't worry about getting messy – it's part of the fun!

Smart Oven Technique

Start hot to get that crust going, then drop the heat for the rest of cooking. Always use a meat thermometer instead of just guessing when it's done. Lamb costs too much to ruin by overcooking!

Patience Pays Off

The toughest part is waiting after it's out of the oven! Your instinct will tell you to cut right in, but those 15-20 minutes of rest make all the difference between juicy meat and dry disappointment. I just cover it loosely and finish up my side dishes while I wait.

I stumbled onto the lamb-mustard combo totally by chance when I ran out of mint jelly one day. I quickly mixed some Dijon with herbs as a last-minute spread, and it turned out so much tastier that I started cooking with it directly!

Pairing Suggestions

This roast goes amazingly with fluffy mashed potatoes or crunchy roasted ones that can soak up all that gravy. For veggies, anything green fits perfectly – try roasted asparagus, green beans, or Brussels sprouts for nice color on the plate. Pop open some red wine (Cab Sauv or Syrah works great) to round everything out.

Customization Ideas

Mix in a spoonful of honey for a sweeter crust. Play with different herbs – mint and oregano give it Mediterranean flair. Want more kick? Stir some horseradish into your mustard mix. A bit of lemon zest can really wake up the flavors too.

Leftovers Advice

Any leftover lamb transforms into knockout sandwiches next day. Just slice it super thin, pile it on good bread with some peppery arugula and a dab of leftover mustard mix. When warming up leftovers, go low and slow – around 300°F wrapped in foil with a splash of broth to keep everything moist.

Tangy Herb-Crusted Mustard Lamb Roast with Savory Drippings Pin it
Tangy Herb-Crusted Mustard Lamb Roast with Savory Drippings | tastybysophie.com

Pro Techniques

  • Get your butcher to butterfly the lamb leg for more even cooking
  • Mix up the mustard coating a day ahead for stronger flavor
  • Get yourself a quality instant-read thermometer – it's the only surefire way to nail the perfect doneness

I used to feel nervous about cooking big hunks of meat, especially something fancy-sounding like lamb. But this dish taught me that sometimes the easiest methods give the most impressive results. The mustard and herbs handle all the flavor work, while your oven does most of the heavy lifting. It's become my go-to impressive meal that looks like I slaved away all day when really I was just chilling with wine while it cooked!

Frequently Asked Questions

→ How can I tell if lamb is medium-rare?
A thermometer should read 135°F inside. Take it out and let it sit for 20-30 minutes.
→ Is it possible to prep ahead?
You can mix the mustard coating the day before, but it’s best to coat and cook on serving day.
→ What should I serve with this lamb?
Try roasted or mashed potatoes, grilled veggies, or a fresh green salad.
→ Can I swap fresh herbs for dried ones?
Sure, if fresh isn’t handy, use a teaspoon of dried rosemary and thyme instead.
→ Why rest the lamb before slicing?
It lets the meat soak up its juices again, giving you a tastier bite.

Mustard Lamb Roast

Boneless lamb leg covered in mustard and herbs, cooked to golden brown with a wine-based sauce on the side.

Prep Time
30 Minutes
Cook Time
150 Minutes
Total Time
180 Minutes

Category: Main Dishes

Difficulty: Intermediate

Cuisine: Mediterranean

Yield: 8 Servings (1 lamb (about 5 lbs))

Dietary: Low-Carb, Dairy-Free

Ingredients

→ Lamb and Marinade

01 1 leg of lamb, boneless (about 5 pounds)
02 2 tablespoons soy sauce
03 ½ cup mustard, dijon-style
04 1 teaspoon dried rosemary
05 1 teaspoon dried thyme
06 3 garlic cloves, minced finely
07 ¼ teaspoon powdered ginger
08 2 tablespoons olive oil

→ Roasting Aromatics

09 Half a small onion, roughly chopped
10 A few sprigs of thyme and rosemary, fresh
11 ½ lemon, sliced into rounds
12 2-4 cups chicken stock

→ Gravy

13 2 tablespoons flour for all-purpose use
14 ½ cup wine, white
15 Salt and pepper for seasoning
16 2-4 tablespoons water, as needed

Instructions

Step 01

Combine mustard, soy sauce, garlic, rosemary, thyme, and ginger in a bowl. Slowly blend in olive oil until thick and creamy, like mayo. Smother the lamb entirely with the mix. Set the lamb (fat side on top) on a rack inside a roasting pan and leave it at room temp for 2 hours.

Step 02

Heat oven to 425°F. Lay the onion chunks, lemon slices, and some fresh herbs beneath the rack in the roasting pan.

Step 03

Put the lamb in the oven at 425°F to roast for around 30 minutes.

Step 04

Turn oven down to 350°F. Keep roasting until the lamb hits your preferred temperature: 135°F for medium-rare or 145°F for medium. Total cook time will run another 90 minutes or so. Pour 2 cups of stock into the pan after the first hour and repeat after another 30 minutes if needed.

Step 05

Take the lamb out when it’s about 5°F below your goal. Move it onto a board, cover loosely with foil, and leave it alone for 20-30 minutes.

Step 06

Drain and skim fat off the pan drippings into a measuring cup. Add chicken stock to reach 2 cups if necessary. Stir together water and flour for a smooth paste. Put the roasting pan over high heat, scrape with wine to loosen browned bits, then boil until it’s reduced by half. Pour in the saved juices and whisk well. Slowly add the paste while whisking nonstop. Let it cook until thick, 5-10 minutes. Add salt and pepper at the end.

Step 07

Cut away any netting or string from the lamb. Slice it into servings and pair with the gravy.

Notes

  1. Leaving the lamb coated in the marinade at room temp boosts its flavor.
  2. Stop cooking the lamb 5°F before your preferred temp—it’ll finish rising while resting.
  3. Letting the meat rest ensures it stays juicy and tender.

Tools You'll Need

  • Roasting rack with a pan
  • Thermometer for meat
  • Foil, aluminum type
  • A whisk
  • Fine-mesh strainer

Allergy Information

Please check ingredients for potential allergens and consult a health professional if in doubt.
  • Includes soy (from soy sauce)
  • Contains wheat (flour, soy sauce)

Nutrition Facts (Per Serving)

It is important to consider this information as approximate and not to use it as definitive health advice.
  • Calories: 375
  • Total Fat: 21 g
  • Total Carbohydrate: 5 g
  • Protein: 35 g