Put the marinade ingredients in a bowl, stir until they are integrated and leave to stand covered in the fridge for at least 15 minutes, preferably overnight.
Strain the tofu and divide into three batches (approximately). Put 1/3 of the tofu cubes in a freezer bag with 2 tablespoons of cornstarch in each batch and shake until well coated. Repeat with the other 2/3 and add more cornstarch if necessary. You can also coat them by tossing the cubes on a plate with cornflour, but the bag technique is easier.
Cook the tofu in a frying pan with a little olive oil until golden brown on all sides. Transfer to a plate and set aside.
If you don't want to use oil, you can bake the tofu at 200C or 400F for about 15 minutes, then turn the tofu cubes over and bake for another 15 minutes or until golden brown all over.
Mix all the sauce ingredients together in a bowl until well blended. Set aside.
Heat a little oil in a frying pan and sauté the vegetables over medium-high heat for about 5 minutes, stirring occasionally.
If you don't want to use oil, you can use water or vegetable stock. Add the ginger and garlic (best in powdered form) and cook for another 1-2 minutes, stirring frequently.
Pour in the sauce and cook until thickened, stirring occasionally. Add the tofu, stir and cook for a further 1-2 minutes. Serve immediately.

For the marinated tofu:
- 200 g firm tofu (12 oz), diced.
- 1/2 tbsp soy sauce or tamari
- 1/2 tbsp apple cider vinegar
- 1/2 tsp cornstarch
To cook the tofu:
- 3 tbsp cornstarch and extra virgin olive oil to taste.
For the sauce:
- 1/4 cup water (125 ml)
- 1.5 tablespoons of soy sauce
- 1 tablespoon cornstarch
- 1/2 tablespoon apple cider vinegar
- 1/2 teaspoon tahini
For the stir-fry:
- Extra virgin olive oil to taste, optional.
- 1 chopped leek
- 1 carrot, chopped
- 1 cm ginger root (1/2 inch), finely chopped