Pat dry and rub pork knuckle with dark soy sauce. Put star anise and Sichuan peppercorn in tea bag.
Heat oil in pressure cooker, add ginger, garlic, and scallion, cook for few minutes. Then add pork knuckle and fry each side until it starts to form some charred marks.
Add star anise, Sichuan peppercorn, dark soy sauce, soy sauce, oyster sauce, cooking wine, rock sugar and water.
Pressure cook for 40 minutes and then check the tenderness. I cooked mine for an hour.
I also added 1 tsp of cornstarch to thicken the sauce.