Here, we make a roulade with a leg of lamb and fill and coat it with fresh mint pesto, which is a refreshing alternative to the traditional mint jelly that often accompanies lamb.
Preheat oven to 350°F.
Place basil, mint, parsley, pine nuts, cheese, oil, garlic, 1/2 teaspoon salt and pepper in a food processor and process until fairly smooth. Sprinkle lamb all over with the remaining 1/2 teaspoon salt. Reserve 2 tablespoons of the pesto; spread the rest over the top side of the lamb and roll it closed. (It will not be a perfect cylinder.) Tie kitchen string around the roast in five places; do not tie too tightly or the pesto will squeeze out. Rub the reserved pesto over the outside of the lamb and place in a roasting pan.
Roast the lamb until a thermometer inserted into the thickest part registers 140°F for medium-rare, about 1 hour 20 minutes. Transfer to a cutting board; let rest for 10 minutes. Carve the lamb, leaving the string in place to help hold the roast together.
Tips: To toast pine nuts, cook in a small dry skillet over medium-low heat, stirring constantly, until fragrant and lightly browned, 2 to 5 minutes. Have your butcher “butterfly” a boneless leg of lamb (that is, open it up to a large, flat cut of meat); ask that any visible fat be trimmed off.