Before cooking, make sure that all vegetables are prepped and ready to go.
For the sauce: In a small jug add the stock, oyster sauce, cornstarch, soy sauce, vinegar, salt and sugar. Mix well.
For the stir-fry: Heat a wok over high heat and as the wok starts to smoke, add the oil. Add the ginger, garlic and chiles, and stir for a second. Add the carrots, peppers and snow peas, then stir-fry for a minute. Toss in the cabbage, kale, mushrooms and tomatoes. Stir-fry for 2 minutes more, adding a splash of water to help the vegetables cook.
Pour the sauce over vegetables in the wok and toss just until the sauce begins to thicken and bubble and becomes glossy. Remove from the heat and toss in the bean sprouts and garnish with scallions. Mix well and serve immediately.