Soak the noodles in hot water for about 3-4 minutes. Don't worry if they are still a bit al dente, they will finish cooking in the wok or pan. Drain and reserve.
Prepare the stir-fry sauce by combining the vegan oyster sauce, dark soy sauce, stock, water, white pepper, and sugar. Mix well until all the ingredients are combined and reserve.
Cut the tofu into cubes. Add some vegetable oil to a pan and pan-fry the tofu. Keep turning the tofu cubes until they are evenly cooked on all sides.
Finely chop or grate the garlic and ginger.
Cut the onion, napa cabbage, bell peppers, carrots, shiitake mushrooms, and scallions into thin slices, and quarter the tomato.
Heat some vegetable oil in a pan or wok to medium-high heat and stir-fry the vegetables, reserving the spring onions for later. Keep stirring to make sure they are cooking evenly. You want the veggies to be cooked while keeping a bit of a crunch.
Add the noodles to the pan or wok, the stir-fry sauce, pan-fried tofu, and spring onions. Stir and cook for 2 more minutes.
Add chopped cilantro, optionally some chili flakes or hot sauce, and drizzle some lime juice.
Serve and enjoy.