Heat oil in a wok or pan over medium heat. When the oil is hot, add the shredded scallops. Fry them on low heat until golden brown. Add the minced garlic and fry until aromatic. Add the prawns and stir-fry until they turn pinkish-orange.
Stir the potato starch mixture again to ensure it’s well combined, then pour it into the wok. Stir until the sauce thickens.
Gently add the tofu cubes to the wok. Season with salt or soy sauce and a pinch of sugar. Cook over medium heat until the mixture gently comes to a boil. Then, reduce to the lowest heat.
Slowly pour the whisked egg whites while gently swirling the sauce with a spatula to create soft ribbons. When the egg whites turn whitish in color, the dish is done.