A simple recipe for p. f. changs copycat mongolian beef. mongolian beef is a dish served in chinese-american restaurants consisting of sliced beef, typically flank steak, and stir-fried with vegetables in a savory brown sauce, usually made with hoisin sauce, soy sauce, and chili peppers. serve this recipe with sriracha and spam fried rice or spicy shrimp and pineapple fried rice. read more about 14 science-backed health benefits of garlic.