Preheat the oven to 180C/350F/Gas 4.
For the tofu, dry the tofu on kitchen paper and chop into cubes. Place the tofu into a non-reactive bowl with the rest of the tofu ingredients, except the oil and coriander, and stir well. Leave to marinate for at least ten minutes.
Heat the oil in a wok and fry the tofu until golden-brown and crisp, about 5-7 minutes. Stir in the coriander.
For the soya bean mash, blanch the beans in boiling water until tender, about 3-4 minutes. Drain the beans and transfer to a food processor. Add the watercress, mint and boiling water and pulse until the beans are mashed but not entirely smooth.
For the balsamic tomatoes, place the tomatoes on a baking sheet and drizzle over the olive oil and balsamic vinegar. Sprinkle with salt and place in the oven to roast for 10-15 minutes.
To serve, place a bed of the soya bean mash on a serving plate and spoon the marinated fried tofu over the top. Serve the roasted balsamic tomatoes to the side and sprinkle over the chopped coriander.