Make the meatballs: Place the pork in a bowl and grate the ginger into the pork. Thinly slice the scallion, add it to the pork. Add salt, white pepper, soy sauce, Shaoxing wine, water, and egg. Stir vigorously with chopsticks until a sticky paste forms (thicker than dumpling filling). With wet hands, roll into ping-pong-sized balls (about 2.5cm/1 inch). Chill in the fridge for 30 minutes if you have time.
Cook the meatballs: Bring water to about 70°C over medium heat, hot but not simmering yet. Gently add the meatballs with a spoon, giving them space. Make sure they don’t stick to the bottom. Gradually bring to a light simmer. Over medium heat, cook the meatballs until pale and floating, about 5-7 minutes. Skim foam.
Add vegetables: Quarter the bok choy from the stem. Add them to the pot and cover. Cook until the greens are wilted, for 2-3 minutes (or 1 minute for tender veggies like pea shoots and spinach). Season with salt, white pepper, black pepper, and sesame oil.
