For rub, combine shallots, garlic cloves, brown sugar, coriander seed, peppercorns, and the 2 teaspoons salt in a food-processor bowl or blender container. Cover and process or blend until coriander seed and peppercorns are coarsely chopped and mixture is combined. Spread shallot mixture over top and sides of meat. Place meat in a plastic bag set in a shallow dish. Close bag. Marinate in the refrigerator for 2 to 24 hours.
For salsa, in a medium mixing bowl combine black beans, mango, sweet and hot peppers, corn, and cilantro. Stir together lime juice, salad dressing, and remaining salt; add to bean mixture, tossing gently to combine. Cover and refrigerate 2 hours to overnight.
To prepare meat, preheat oven to 425 degree F. Remove meat from bag. Place meat on rack in a shallow roasting pan. Replace any shallot mixture that may have fallen off. Bake, uncovered, for 30 to 45 minutes or until meat thermometer registers 145 degree F (medium rare). Cover meat with foil; let stand 10 minutes before slicing. Serve with salsa. Makes 8 to 10 servings.