Line a sieve with kitchen paper or a clean cloth, carefully place the tofu in the sieve and allow to drain over a bowl for at least 10 minutes. Place the cumin seeds in a pestle and mortar and crush to a coarse powder. Heat the oil in a non-stick frying pan and, when hot, add the ground cumin seeds. Stir-fry for a minute until the smell rises, then add the onion. Fry for 8 minutes until soft, sweet and browning, and add the chilli, garlic and ginger. Fry for 2 minutes, then add the tomato, coriander, turmeric and salt. Take the tofu and crush it between your fingers into the pan (or mash it in the pan with a potato masher). Cook for a few more minutes, until the tofu is piping hot and well mixed with the other ingredients, then serve immediately on toast, drizzled with oil if you wish, alongside ketchup and a pot of chai.