1 boneless leg of lamb (4 to 5 pounds)--trimmed, rolled and tied
Salt and freshly ground black pepper
1 pound merguez or hot Italian sausage, casing removed and crumbled
1 cup diced onion
1 ripe Roma tomato, cored and diced
½ cup diced fennel
½ cup diced carrot
½ cup sherry wine vinegar
¼ cup basil leaves, chopped
15 oregano leaves, chopped
⅛ teaspoon red-pepper flakes
Directions
Preheat the oven to 375°. Season the leg of lamb liberally with salt and pepper and place on a roasting rack fit inside a roasting pan. Transfer the lamb to the oven and cook until an instant-read thermometer registers 130° for medium rare, about 45 minutes. Remove the pan from the oven, tent with foil and allow the lamb to rest while you make the merguez vinaigrette.
Heat a large skillet. Add the sausage and cook over medium-high heat until cooked through and browned, about 10 to 12 minutes. Using a slotted spoon, transfer the sausage to a plate, leaving the fat in the pan. Add the onion, tomato, fennel and carrot to the pan and cook, stirring occasionally, until tender, about 8 minutes. Add the sherry vinegar and whisk to incorporate any browned bits from the bottom of the pan. Remove from the heat and stir in the sausage, basil, oregano and red-pepper flakes. Season to taste with salt and black pepper.
To serve, cut the leg of lamb into 1/2-inch slices, divide among plates and top with the merguez vinaigrette.