Soak chilies in water until softened; remove seeds. Reserve soaking liquid.
Process chilies, vinegar, garlic, Knorr® Beef flavor Bouillon, sugar, paprika and 2 to 3 tablespoons reserved soaking liquid in blender until smooth. Rub all over ribs. Place ribs in large, shallow nonaluminum baking dish. Cover and marinate in refrigerator overnight.
Preheat oven to 300°. Arrange ribs meaty side up in large roasting pan. Top with any chili mixture left in baking dish. Cover tightly with aluminum foil.
Bake 2 1/2 hours or until ribs are tender. Garnish, if desired, with chopped fresh cilantro or parsley.