Any cut of lean pork can be used to make this soup. Think of the meat as a condiment--use just enough for flavor and texture. Chicken can also be substituted, if desired. You can adjust the heat and sourness to taste by increasing or decreasing the vinegar and pepper.Tofu is a great source of soy protein and omega-3 fatty acids. It's also an excellent way to get iron, which is why it's prominent in vegetarian diets.