Prepare the mushrooms : Soak the dried shiitake mushroom in water until fully softened. Squeeze out excess liquid, then finely dice or mince. Set aside.
Prepare the sauce : In a small bowl, combine all the sauce ingredients. Mix well and set aside.
Prepare the tofu : Pat the firm tofu dry with kitchen paper. Cut into 4×4×2 cm cubes (you should get about 10 pieces from 375 g tofu).
Scoop the centres : Using a small spoon, carefully scoop out the centre of each tofu cube to create a cavity. *Tip: Lightly score a small rectangle in the centre with a knife first for cleaner edges. Reserve the scooped-out tofu (about 60–75 g).
Make the pork filling : In a bowl, combine the pork mince, reserved tofu, spring onion whites, minced shiitake mushroom, soy sauce, cooking wine,white pepper, sugar, salt, and cornstarch. Mix thoroughly, then slap or throwthe mixture against the bowl several times until it becomes sticky and well bound.
Stuff the tofu : Lightly dust the cavity of each tofu piece with a small amount of cornstarch (this helps the filling adhere). Pack the pork filling firmly into each cavity, levelling the top. Lightly dust the surface with a little more cornstarch.
Pan-fry : Heat a sufficient amount of oil in a pan over medium-high heat. Place the tofu pork-side down and cook until the filling is golden and set. Turn gently and fry the other sides of the tofu until lightly golden. (Cook in batches if necessary.)
Braise : Pour in the prepared sauce, reduce the heat to medium-low, cover with a lid, and simmer for 6–8minutes, allowing the pork to cook through and the tofu to absorb the sauce.
Finish and serve : Uncover the pan and spoon the sauce over the tofu. Continue cooking for a few more minutes until the sauce slightly thickens. Transfer to a serving plate, drizzle with the remaining sauce, and garnish with shredded spring onions and sliced chillies before serving.