Slow-Roasted Lamb with Rosemary and Parkland Mint Sauce

By , Test Kitchen Director · Reviewed by AislePrompt Editorial · ·

Succulent slow-roasted lamb infused with rosemary, paired with a refreshing mint sauce reminiscent of London's royal gardens. This british-inspired lamb ready in about 170 minutes blends leg of lamb, fresh rosemary sprigs, garlic cloves, sliced into a versatile sauce that lifts everything from grain bowls and roasted vegetables to grilled proteins — a small-batch staple worth keeping in the fridge. Each serving lands at about 480 calories and feeds 6, so a small batch covers several meals across the week without taking over the fridge. 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.

Prep: 20 min Cook: 150 min Serves 6 British cuisine 480 cal/serving
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Ingredients

Instructions

  1. Step 1: Preheat oven to 325°F. Using a sharp knife, make 12 small incisions all over the 4 lb leg of lamb and insert 6 sliced garlic cloves and 4 fresh rosemary sprigs evenly.
  2. Step 2: Rub the lamb with 3 tbsp olive oil, then season generously with 2 tsp salt and 1 tsp black pepper. Place in a roasting pan and roast for 2 to 2.5 hours until an internal temperature of 135°F for medium-rare is reached.
  3. Step 3: While the lamb cooks, prepare the mint sauce by finely chopping 1/2 cup fresh mint leaves and combining them with 2 tbsp white wine vinegar, 1 tsp sugar, and 1/4 cup water in a small bowl. Stir until sugar dissolves and set aside.
  4. Step 4: Remove the lamb from the oven and cover loosely with foil. Let rest for 15 minutes before slicing. Serve with the mint sauce drizzled on the side for a classic pairing that evokes the tranquility of London's royal parks.

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Frequently asked questions

How long does Slow-Roasted Lamb with Rosemary and Parkland Mint Sauce take to make?

Total time is about 170 minutes (20 min prep + 150 min cook). A small batch typically covers several meals in the week — store as the recipe directs.

How do I store leftover Slow-Roasted Lamb with Rosemary and Parkland Mint Sauce?

Transfer to an airtight jar and refrigerate for up to 5–7 days. Most sauces freeze well for up to 2 months — portion into small containers or freezer bags so you can thaw only what you need. Stir before serving; cream- or yogurt-based sauces may separate on standing.

Can I substitute ingredients in Slow-Roasted Lamb with Rosemary and Parkland Mint Sauce?

Yes — most ingredients in this recipe have flexible swaps. For oil, use any neutral high-smoke-point oil (avocado, grapeseed, refined coconut). For aromatics, dried herbs at ⅓ the volume of fresh work in a pinch. The full ingredient list is shoppable on Instacart so you can see substitutes in real time.

How do I scale Slow-Roasted Lamb with Rosemary and Parkland Mint Sauce for a different number of people?

The recipe is written for 6 servings. Multiply each ingredient by (your serving target / 6). Cook time stays roughly the same up to 2x; for 3-4x batches, switch from a skillet to a sheet pan or stockpot so the food isn't crowded — overcrowding steams instead of browns.

What goes well with Slow-Roasted Lamb with Rosemary and Parkland Mint Sauce?

British lamb like this pair well with a simple grain (rice, couscous, or crusty bread), a quick salad with acid (lemon vinaigrette, pickled onions), and a pan sauce or yogurt-based dip. Tap "Plan a meal with the AI" to get specific side suggestions.

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