The cooking time depends on how big your rack of lamb is, and how rare you want it cooked. Rack of lamb should be cooked rare, or at most medium rare. The instructions are for a rack 1 1/4 to 2 pounds big. If you are cooking multiple racks (unless you are doing a crown roast which is a different matter), lay them out separately on the pan, and you may need to increase the cooking time.
Use a meat thermometer! Many factors can affect cooking time like the shape of the roast, the fat marbling, and your individual oven characteristics. This is too lovely and tender a roast to risk overcooking.
Make sure to allow enough time for your rack of lamb to come close to room temperature before cooking. Otherwise the inside will still be raw while the outside is cooked.
- 1 or more Frenched* lamb rib racks with 7 to 8 ribs each (1 1/4 to 2 pounds for each rack, figure each rack feeds 2-3 people)
For each rib rack:
- 2 teaspoons chopped fresh rosemary
- 1 teaspoon chopped fresh thyme
- 2 cloves garlic, minced
- 2 Tbsp olive oil
*Typically you will buy a rack of lamb already "Frenched", or cut so that the rib bones are exposed. You can also ask your butcher to french them for you. For directions on how to French them yourself, see How to French a Rack of Lamb.
1 Marinate lamb in rub: Rub rib rack(s) all over with mixture of rosemary, thyme, and garlic. Sprinkle with freshly ground black pepper. Place in a thick plastic bag with olive oil.
Spread oil around so that it coats the lamb rack(s) all over. Squeeze out as much air as you can from the bag and seal. Place in a container so that if the bag leaks, the container catches the leak.
If you want, place in the refrigerator overnight. Or, if you are not marinating overnight, let lamb rack(s) sit in the rub marinade as it comes to room temperature before cooking.
2 Bring lamb to room temp: Remove lamb rack from refrigerator to 1 1/2 to 2 hours before you cook it so that it comes to room temp. (If the meat is not at room temperature it will be hard for it to cook evenly.)
3 Preheat oven to 450°F, arrange the oven rack so that the lamb will be in the middle of the oven.
4 Score the fat, sprinkle with salt and pepper, wrap bones in foil, place in pan fat side up: Score the fat, by making sharp shallow cuts through the fat, spaced about an inch apart.
Sprinkle the rack all over with salt and pepper. Place the lamb rack bone side down (fat side up) on the pan. Wrap the exposed ribs in a little foil so that they don't burn.
5 Roast first at high heat to brown, then reduce heat to finish: Place the roast in the oven roast at 450°F for 10 minutes (longer if roasting more than one rack), or until the surface of the roast is nicely browned.
Then lower the heat to 300°F. Cook for 10-20 minutes longer (depending on the size of the lamb rack, if you are roasting more than one rack, and how rare or well done you want your lamb), until a meat thermometer inserted into the thickest part of the meat 125°F on a for rare or 135°F for medium rare. Remove from oven, cover with foil and let rest for 15 minutes.
Cut lamb chops away from the rack by slicing between the bones. Serve 2-3 chops per person.