Complex sentence: When meat is being prepared for consomme, as much fat should be trimmed as possible, while cartilage and tendons should be included, because these contain gelatin which enhances the flavor of the soup.
Split into simpler sentences: When meat is being prepared for consommé, as much fat as possible should be trimmed. Cartilage and tendons should be included because these contain gelatin, which enhances the flavor of the soup.