Preparation : clean and cut yellow onion, red and green bell peppers, king oyster mushrooms, and baby Bok Choy. Meanwhile, place all the ingredients for the stir-fry sauce in a bowl, combine all of them together then set aside.
Heat oil in a wok or skillet over high heat. Add sliced yellow onion, toss quickly, then top with tofu puffs. Cook for 1 minute, stirring constantly, until onion is starting to wilt.
Pour the stir fry sauce mixture into the work and mix well, making sure everything is coated with the sauce. Cook for 2-3 minutes until the sauce is thickened.