Cut the tofu into 1" cubes and add to a large mixing bowl. Add the oil, soy sauce, garlic powder, onion powder and corn starch. Mix very gently with a flat spoon, so you don't make the tofu crumble.
16 ounce block of extra firm tofu, 2 tablespoons soy sauce, 1 tablespoon oil, 1 teaspoon garlic powder, 1 teaspoon onion powder, 1 tablespoon corn starch