How to make it
Soak the shiitake mushrooms in 300ml hot water for a minimum of 2 hours, or ideally overnight, then drain, reserving the soaking water. Finely slice the ginger and roughly chop the spring onion. Slice the pak choi into quarters, lengthways.
Press the fresh tofu for 15 minutes by placing a couple of pieces of kitchen paper on a large plate, followed by the tofu, topped with a couple more sheets of kitchen paper and another large plate. Place a few cans or cookbooks on top to weigh it down.
Finely chop the soaked mushrooms, prawns (if using), garlic, ginger and spring onion and place in a large mixing bowl. Top and tail the green beans and finely chop. Add the pressed tofu into a mixing bowl with the beans and all the remaining tofu mix ingredients apart from the cornflour and egg yolk. Use your fingertips to break the tofu up, creating a thick paste. Add the cornflour and egg yolk, mix well and set aside.
Mix the sauce ingredients together in a bowl. Lastly, mix 1 tablespoon of cornflour and 3 tablespoons of water to make a paste. For deep frying, half-fill a medium pot, wok or deep-fryer with vegetable oil and heat to 180°C (350°F), or use a wooden skewer or wooden chopstick to test by placing the tip into the oil: if the wood starts to fizz after a second or so, the oil is hot enough. You can also shallow fry these for a slightly healthier alternative, though do so with extra care when turning them over to cook on all sides, so as not to break up your quenelles.
Using 2 dessert spoons, carefully ‘quenelle’ the tofu, then lay a quenelle of tofu mix in the hot oil. Alternatively, form little balls out of the mixture and fry the tofu in ball shapes instead. Fry in batches of 5 or 6 at a time, keeping the oil at a high temperature, until golden brown all over, roughly 3–4 minutes if deep frying or 5-6 minutes (turning over until all sides are golden) if shallow frying, then remove from the hot oil with a slotted spoon or a Chinese frying skimmer and drain on kitchen paper. Repeat until all your tofu mixture has been used up.
Now heat 1 tablespoon of vegetable oil in a medium saucepan or claypot to a medium-high heat. Add the sliced ginger and roughly chopped spring onion and stir through for 30–60 seconds. Pour the sauce into the pan and bring to the boil, then add the pak choi and cook in the sauce for 2 minutes. Place the pak choi in a serving dish. Stir the cornflour paste into the sauce and bring to the boil. Add the fried tofu pieces to the pan and continue boiling for 1–2 minutes, carefully coating the tofu quenelles with the sauce. Pour the tofu and sauce over the pak choi and serve.