Herb-Crusted Mustard Lamb Roast

I made this mustard lamb roast for Easter dinner last year, and my mother-in-law actually asked me for the recipe - which is basically the cooking equivalent of winning an Olympic gold medal! The herb-mustard coating creates this incredible crust that seals in all the juices, making even lamb skeptics come back for seconds.

My brother, who swore he "doesn't like lamb," had three helpings and then casually asked if I could "maybe make this again sometime" when he visits next month.

What You'll Need

• Boneless leg of lamb: Australian or New Zealand lamb has a milder flavor that even people who think they don't like lamb will enjoy.
• Dijon mustard: Creates that tangy base for the herb crust. Whole grain works too for extra texture.
• Fresh herbs: Rosemary and thyme are traditional with lamb and worth buying fresh for this dish.
• Garlic: Don't be shy here - the robust flavor stands up perfectly to the lamb.
• Soy sauce: Just a touch adds depth without making it taste Asian-inspired.
• White wine: Helps create that amazing pan sauce and tenderizes the meat.
• Good quality olive oil: Helps the crust adhere and adds richness.

Pin it

How I Make It

Perfect Prep

I always pat the lamb completely dry with paper towels before applying the mustard mixture. This helps the coating stick better and creates a more intense flavor. Bringing the meat to room temperature is non-negotiable - it makes such a difference in how evenly it cooks.

Mustard Magic

The mustard mixture gets slathered generously all over the lamb, working it into all the nooks and crannies. I've found using my hands works best for this, really massaging it in. Don't be afraid to get messy!

Roasting Right

Starting with a hotter oven to develop a crust, then lowering the temperature ensures perfect cooking. I always use a meat thermometer rather than relying on timing - lamb is too precious (and expensive) to risk overcooking.

Resting Rewards

The hardest part is waiting while it rests! It's so tempting to cut right in, but those 15-20 minutes make all the difference between juicy perfection and dry disappointment. I cover it loosely with foil and use this time to finish my side dishes.

I discovered the power of mustard with lamb completely by accident when I was out of the mint jelly I usually served on the side. I mixed some Dijon with herbs as a quick alternative spread, and it was so much better that I started incorporating it directly into the cooking process!

Serving Ideas

This roast pairs beautifully with creamy mashed potatoes or crispy roasted potatoes that can soak up the gravy. For vegetables, anything green works well - roasted asparagus, green beans, or Brussels sprouts provide nice color contrast. A good bottle of red wine (Cabernet Sauvignon or Syrah) completes the meal perfectly.

Make It Your Own

Add a tablespoon of honey to the mustard mixture for a slightly sweeter crust. Try different herb combinations - mint and oregano offer Mediterranean vibes. For a spicier version, mix some horseradish into the mustard coating. You can also add lemon zest to brighten up the flavors.

Practical Storage

Leftover lamb makes incredible sandwiches the next day. Slice it thin and pile on good bread with some arugula and a smear of the leftover mustard mixture. For reheating, I find low and slow is best - about 300°F covered with foil and a splash of broth to keep it moist.

Pin it

Chef's Secrets

• Ask your butcher to butterfly the lamb leg - it helps it cook more evenly
• For an even more intense flavor, make the mustard coating the night before
• Invest in a good instant-read thermometer - it's the only way to ensure perfect doneness

I used to be intimidated by cooking large cuts of meat, especially something as seemingly fancy as lamb. But this recipe taught me that sometimes the simplest preparations yield the most impressive results. The mustard and herbs do all the heavy lifting flavor-wise, while the oven does most of the work. It's become my secret weapon recipe that looks like I spent all day in the kitchen when really I was relaxing with a glass of wine while it roasted!

Frequently Asked Questions

→ How do I know when my lamb is cooked to medium-rare?

Use a meat thermometer to check for an internal temperature of 135°F, then remove from oven and let rest for 20-30 minutes.

→ Can I make this recipe ahead of time?

You can prepare the mustard coating a day ahead, but for best results, coat the lamb and roast it the day you plan to serve it.

→ What sides go well with this lamb roast?

Roasted potatoes, grilled vegetables, fresh salad, or creamy mashed potatoes complement this lamb roast beautifully.

→ Can I use dried herbs instead of fresh for the roasting pan?

Fresh herbs add more aroma, but if unavailable, use 1 teaspoon each of dried rosemary and thyme instead.

→ Why does the lamb need to rest before carving?

Resting allows juices to redistribute throughout the meat, resulting in a juicier, more flavorful roast.