Slow-Roasted Lamb Shoulder with English Mustard and Rosemary

By AislePrompt Editorial · Published 2026-05-08 · Updated 2026-05-08

A tender, slow-roasted lamb shoulder infused with fragrant rosemary and a sharp English mustard crust, perfect for a cozy British Sunday dinner. This British-inspired lamb recipe, ready in about 230 minutes, pairs lamb shoulder, English mustard, fresh rosemary for a weeknight-friendly dinner that comes together with one pan and minimal cleanup. Each serving lands at about 480 calories and feeds 6, so it slots cleanly into a weekly meal plan and pairs well with a quick salad or grain on the side. Tap "Plan a meal with the AI" below to drop this recipe into your week and send the ingredients straight to Instacart. Nutrition values are approximate, calculated from USDA FoodData Central (fdc.nal.usda.gov) — verify against ingredient labels for any health-driven dietary plan.

Ingredients

• 3 lbs lamb shoulder
• 3 tbsp English mustard
• 2 tbsp chopped fresh rosemary
• 4 minced garlic cloves
• 2 tbsp olive oil
• 1 tbsp sea salt
• 1 tsp freshly ground black pepper
• 1 cup water

The roasting pan we’d use for this → Best Roasting Pans for 2026: Racks, Handles & Sizes for the Holiday Bird

Instructions

1. Step 1: Preheat oven to 325°F. Pat dry 3 lbs lamb shoulder with paper towels. Mix 3 tbsp English mustard, 2 tbsp chopped fresh rosemary, 4 minced garlic cloves, 2 tbsp olive oil, 1 tbsp sea salt, and 1 tsp freshly ground black pepper in a small bowl.
2. Step 2: Rub the mustard-herb mixture evenly all over the lamb shoulder. Place the lamb in a roasting pan and pour 1 cup water into the bottom to keep it moist.
3. Step 3: Cover the roasting pan tightly with foil and roast for 3 hours until the lamb is tender and falling apart. Remove foil for the last 30 minutes to brown the crust.
4. Step 4: Let the lamb rest for 15 minutes before carving. Serve with roasted vegetables and mint sauce.