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Slow Roast Lamb Recipe

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Prep Time 15 minutes
Cook Time 4 hours
Total Time 4 hours 15 minutes
Servings: 6 servings
Course: Main Course
Ingredients Method

Ingredients
  

  • For the Lamb
  • 4 lb –5bone-in leg of lamb
  • 2 tablespoons olive oil
  • 1 tablespoons ½kosher salt
  • 1 teaspoon black pepper
  • 1 large onion quartered
  • 1 whole head garlic halved crosswise
  • 3 –4 sprigs fresh rosemary
  • 2 sprigs thyme optional
  • For the Roasting Liquid
  • 2 cups low-sodium beef broth
  • 1 cup water or dry white wine
  • For the Gravy
  • 1 cup pan juices after roasting
  • 1 tablespoon all-purpose flour or cornstarch slurry
  • Salt and pepper to taste

Method
 

  1. Prep the Oven Preheat to 325°F. Not higher. Low heat is key.
  2. Season the Lamb Pat the lamb dry. Rub with olive oil, salt, and pepper. Don’t be shy—this is a large cut. If you want extra flavor, make small slits and tuck thin garlic slices inside.
  3. Build the Aromatic Bed Place onions, garlic halves, and herbs in a large roasting pan. Set the lamb on top, fat side up. The fat will slowly baste the meat as it cooks.
  4. Add Liquid (But Not Over the Lamb) Pour broth and water around the base. Keep the top dry so it can brown later.
  5. Cover and Slow Roast Cover loosely with foil. Roast for about 4 hours. Internal temperature for fall-apart texture: 190–195°F. For sliceable medium: 135–140°F (pull earlier). Here’s the contradiction—slow roast lamb isn’t meant to be pink and delicate. It’s meant to be tender and relaxed. But you can choose.
  6. Brown the Top Remove foil. Increase heat to 400°F and roast 20–30 minutes until golden. That final blast gives texture contrast.
  7. Rest (Don’t Skip This) Let it rest 15–20 minutes. Juices redistribute. Cutting too soon means losing flavor. And patience here pays off.
  8. Make Quick Pan Gravy Strain pan juices into saucepan. Skim fat. Whisk 1 tablespoon flour into 1 cup liquid. Simmer until thickened. Taste. Adjust salt. That’s it.