Track your Pure Bred lamb

Roasted Lamb Loin with Pommes Boulangère

Provided by: Thomas Keller

Serves 8-10


  • 1 each lamb loin roast (about 6½ pounds)
  • 2 each large rosemary sprigs
  • 4 each cloves garlic, peeled, crushed
  • Black pepper from a mill
  • Kosher Salt
  • 1½ kilograms / 3½ pounds Yukon gold potatoes, medium sized (about 4 ounces each)
  • 450 grams / 1 pound (about 2 each large) yellow onions
  • 450 grams / 2 cups chicken stock
  • 60 grams / 2 ounces butter
  • 20 grams / 2 tablespoons kosher salt
  • 9 grams / 3 tablespoons thyme, finely chopped
  • 1 each large clove garlic, peeled, lightly crushed
  • 1 each bay leaf
  • 7½ grams / 2 tablespoons parsley, minced
  • Coarse finishing salt (such as sel gris)
  • Note: For best results, we recommend that this recipe be completed over the course of two days. If desired, this recipe can be completed in one day.

method (day 1):

  1. Remove lamb from packaging and pat dry with paper towels.
  2. Roll netting halfway down length of roast, but do not remove.
  3. Season un-netted half with kosher salt and freshly ground pepper. Also season interior surfaces. Replace netting.
  4. Roll netting away from unseasoned side and repeat seasoning process. Insert rosemary sprigs and 4 crushed garlic cloves into center of roast. Replace netting.
  5. Store lamb in refrigerator to allow exterior surfaces to dry.

method (day 2):

  1. Allow lamb to temper outside of refrigerator for at least 1 hour and 30 minutes before roasting.
  2. While meat tempers, preheat oven to 350˚F and adjust oven rack to just below center.
  3. While lamb is resting and oven is pre-heating, slice potatoes and onions 1/8” thick using a mandoline (or a sharp knife).
  4. Place potatoes and onions in an 11”x15” roasting pan and toss to evenly distribute.
  5. Combine chicken stock, butter, 2 tablespoons salt, thyme, bay leaf and 1 lightly crushed garlic clove in a sauce pot.
  6. Bring liquid to a boil and cook until butter has melted and emulsified into stock.
  7. Pour stock over potatoes and onions. Stir well to distribute.
  8. Press potatoes into single flat layer (or as close to a single layer as possible). Liquid does not have to cover potatoes fully.
  9. Wrap roasting pan in aluminum foil and bake for 1 hour.
  10. Remove pan from oven and remove foil. Place loin roast in center of pan.
  11. Increase temperature to 375˚F and return pan to oven. Roast for 1 hour.
  12. Remove pan from oven, turn roast over and continue cooking, 45 minutes.
  13. Insert digital probe thermometer into center of roast and continue to cook until lamb has reached 128˚F.
  14. Remove pan from oven and transfer lamb to a platter to rest, about 30 minutes, in warm area prior to carving.
  15. If potatoes still contain liquid return to oven. Cook until liquid has evaporated and top layer is golden brown.
  16. When finished cooking, sprinkle potatoes with minced parsley.
  17. Remove netting from roast, discard rosemary and garlic and carve into ½” thick slices. Arrange on a platter.
  18. Sprinkle lamb with a few grains of finishing salt.
  19. Serve with pommes boulangère.

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