Step 2
Cook the pork topping: Heat oil in saucepan over medium heat, and add ground pork and salt. Pan-fry, breaking meat into small pieces with a wooden spoon, until no pink parts and no liquid remain in the pan, about 5 minutes. Add garlic, ginger and scallion whites, and stir occasionally until the raw smell has disappeared and the meat is starting to brown in places, about 5 minutes. Add the vegetables, if using, along with a tablespoon of water, and cook for 2 or 3 minutes more, or until mixture is darkened and thick. Set aside.