Step 1

Preheat the oven to 425 degrees F.

Step 2

Cut 8 small slits over the surface of the lamb. Tuck a half garlic clove in each slit.

Step 3

Using kitchen string, tightly tie the lamb in several places (see photo above).

Step 4

In a small bowl, stir together the olive oil, rosemary, salt and pepper. Rub the rosemary mixture over the surface of the lamb.

Step 5

Place the leg of lamb in a roasting pan or on a rimmed baking sheet. Cook at 425 degrees F for 15 minutes.

Step 6

Decrease the heat to 350 degrees F and roast until a thermometer inserted into the thickest part of the meat reads 130 degrees F, about 1 ¼ hours. In the last 5 minutes of cooking, brush the lamb with 1/3 of the glaze.

Step 7

Transfer to a cutting board and let rest for about 20 minutes. The temperature will rise about 10 degrees as the lamb rests, bringing it to medium-rare.

Step 8

Brush the lamb with another 1/3 of the glaze. Slice against the grain. Serve with remaining glaze.

Step 9

In a small, whisk together the blackberry preserves, Worcestershire sauce and apple cider vinegar.