Trim fat from lamb. Cut slits in meat; insert garlic. Drizzle with lime juice. Combine oregano, coriander, thyme, cumin, chili powder and salt; rub over meat. Place on a rack in a roasting pan. Insert meat thermometer without touching bone. Roast in a 325 degree F oven for 2 1/2 to 3 hours or until thermometer registers 145 degrees F to 155 degrees F.
Let stand. Skim fat from juices. In a saucepan combine 2 tablespoons of the juices and the onion; cook until onion is tender. Stir in drained beans, peppers, pimiento, cilantro, and vinegar. Bring to boiling; reduce heat. Cook 5 minutes. Serve with lamb. Makes 10 to 12 servings.