Heat the oil in a wok or large frying pan until starting to smoke, add the tofu and stir-fry over a high heat for 2 minutes until golden. Remove from the pan and keep warm.
Add the ginger, prepared vegetables and cashews to the pan and stir-fry for 5 minutes, or according to packet instructions, until the vegetables are tender and the cashews are lightly golden.
Stir in the oyster sauce and black bean sauce and return the tofu to the pan. Cook for 1 minute, then serve immediately with noodles.