Heat the vegetable oil in a large frying pan.
Place the whole block of tofu on a plate, cover with another plate and put something heavy on top, like a book, to press the tofu and get rid of excess water. Keep it that way for about 15 minutes. It will help the tofu get all crispy and lovely. Then cut the tofu in cubes.
In a mixing bowl, add the cornflour, seasoning, chilli flakes, bicarbonate of soda, minced ginger and garlic, and vinegar; mix well and add a couple of tbsp of water to make a thick batter. When all combined, add the cubed tofu and toss well to coat evenly.
Once the oil is hot, carefully add the tofu. Fry until crispy and golden for about 7 minutes, then remove and place on kitchen paper to drain.
In a large frying pan, heat the vegetable oil until really hot. Add the sliced onion and peppers, minced garlic and ginger, and chilli or Sriracha sauce. Stir fry for two minutes, then add the rest of the sauce ingredients. Leave to bubble until thickened and caramelised, for about 7 minutes.
Add the tofu to the pan and stir to coat evenly. Leave it there until just before serving so the tofu will remain crispy. If this goes above 5 minutes, reduce the heat.
Serve with rice noodles or brown rice. Top with coriander leaves and peanuts if liked.