Soak the tofu in a heatproof bowl of just-boiled water and set aside for 10 minutes.
Meanwhile, heat the sesame oil in a large frying pan or wok over a medium to high heat and add the mushrooms, the white part of the spring onions, the ginger and garlic. Stir-fry for 10 minutes until the moisture has evaporated from the mushrooms. Drain the tofu and pat dry with kitchen paper.
Add the chilli bean paste and black bean sauce (or their substitutions) to the pan and stir-fry for 30 seconds before adding the water. Stir through, then add the drained tofu and gently stir to mix. Bring to the boil, then gently simmer for 2–3 minutes, adding the remaining sliced spring onion greens for the last 2 minutes. Taste and adjust the salt as needed.
Scatter over the ground Sichuan peppercorns (if using), and serve hot with fluffy white rice.
