Boneless leg of lamb would seem to be an easy dinner; after all, it already comes boned, rolled, and tied. But it’s not as simple as seasoning the lamb, throwing it in the oven, and then checking on it occasionally. We wanted a foolproof method for achieving a crisp crust and perfectly cooked interior every time. We first settled on a half leg as the right amount to serve four to six people. Searing the roast on the stovetop jump started the cooking process and ensured a golden-brown crust, while finishing it in a 375-degree oven allowed the meat to cook through at an even rate, guaranteeing a juicy and tender interior. A savory crumb crust flavored with fresh herbs, garlic, and some Parmesan was a welcome addition to our roast. To prevent the crust from falling apart once the twine was cut, we cut the twine halfway through cooking, after the lamb had roasted long enough to hold its shape and then applied the crust to the lamb. We prefer the sirloin end rather than the shank end for this recipe, though either will work well. We prefer this roast cooked to medium, but if you prefer it more or less done, see our guidelines. Serve with Fresh Mint Relish, if desired.
Ingredients
- 1 slice hearty white sandwich bread
- ¼ cup extra-virgin olive oil
- ¼ cup minced fresh parsley
- 3 tablespoons minced fresh rosemary
- 2 tablespoons minced fresh thyme
- 3 garlic cloves, peeled
- 1 ounce Parmesan cheese, grated (½ cup)
- 1 (3½-to 4-pound) boneless leg of lamb, trimmed
- Salt and pepper
- 1 tablespoon Dijon mustard
- Adjust oven rack to lower-middle position and heat oven to 375 degrees. Pulse bread in food processor until coarsely ground, about 10 pulses (you should have about 1 cup crumbs); transfer to bowl. In now-empty processor, process 1 teaspoon oil, parsley, rosemary, thyme, and garlic until minced, scraping down sides of bowl as needed, about 1 minute. Transfer 1½ tablespoons herb mixture to second bowl; set aside. Scrape remaining mixture into bowl with bread crumbs; stir in Parmesan and 1 tablespoon oil and set aside.
- Lay lamb with rough interior side (which was against bone) facing up and pound to even ¾-inch thickness; rub with 2 teaspoons oil and season with salt and pepper. Spread reserved herb mixture evenly over meat, leaving 1-inch border around edge. Roll roast into tight cylinder, then tie with kitchen twine at 1-inch intervals. Season with salt and pepper, then rub with 1 tablespoon oil.
- Set wire rack in rimmed baking sheet. Heat remaining 1 tablespoon oil in 12-inch skillet over medium-high heat until just smoking, about 3 minutes. Sear lamb until well browned on all sides, about 8 minutes. Using tongs, stand roast on each end to sear, about 30 seconds per end. Transfer to rack and roast until meat registers 120 degrees, 30 to 35 minutes.
- Transfer roast to carving board and remove twine. Brush lamb exterior with mustard, then carefully press bread-crumb mixture onto top and sides of roast with your hands, pressing firmly to form solid, even coating that adheres to meat. Return coated roast to rack; roast until meat registers 130 to 135 degrees (for medium), 15 to 25 minutes longer.
- Transfer roast to carving board, tent loosely with aluminum foil, and let rest for 15 minutes. Cut into ½-inch-thick slices and serve.
