Soak dry oysters in water for 15 minutes. Drain through a sieve, reserving the soaking water for use in the recipe. Rinse pork and cut into 2-cm wide strips. Place them in a pot filled with enough water to just cover the pork. Pour in vinegar and 1 tablespoon of rice wine. Bring it to a boil over medium heat. Skim, reduce the heat and cook 2-3 more minutes. Turn off the heat and scoop out the pork. Rinse under tap water and drain thoroughly.
Heat up a skillet with oil. Add in rock sugar and stir until caramelized. Stir in scallion, ginger, garlic, peppercorns, pickled chillies and pork. Stir in black mushrooms and dried oysters. Pour in soya sauces, oyster sauce and rice wine. Toss all the ingredients together.
Pour the whole mass into an electric pressure cooker. Pour in the reserving soaking liquid, which should barely cover the ingredients. Add in anise star and salt. Close the lid and turn the knob to pork cooking cycle. After cooking, the cooker automatically enters the "keep warm" status. After cooling, return the pork mass into the frying pan and stir over the high heat until the whole mixture comes together into a sticky, gooey mass. Season with chicken bouillon and dish off.