In a large bowl combine the pork, egg whites, water chestnuts, 2 tablespoons of the cornstarch, Shaoxing wine, 2 tablespoons of the light soy sauce, ginger, garlic, scallion whites, sesame oil and white pepper. Stir hard in one direction with a spatula or your hand for 2 to 3 minutes, until the mixture turns sticky and paste-like and starts pulling away from the bowl.
That one-direction stirring is the whole trick. Working the mince in a single direction lines up the proteins so the meatballs turn springy and bounce instead of falling apart, the texture that gives lion's head its name.
Divide the mixture into 4 and shape each portion into one big meatball, about the size of a tennis ball. Wet your hands and toss each ball firmly between your palms a few times to compact it and knock out air pockets. The large size is not for show, it is what keeps the centers juicy through the braise.
Heat the neutral oil in a wide Dutch oven or deep skillet over medium-high. Gently lower in the meatballs and brown them on two or three sides, about 4 minutes total, just to set a skin. They will not be cooked through and they are fragile at this stage, so turn them carefully with two spoons. Lift them out to a plate.
Add the napa cabbage to the same pot and stir for about 2 minutes, until it starts to wilt and picks up the browned bits stuck to the bottom. Spread it into an even bed.
Pour in the chicken broth, the remaining 1 tablespoon light soy sauce, the oyster sauce, dark soy sauce and sugar. Nestle the meatballs on top of the cabbage. Bring to a gentle simmer, cover, and cook on low for 40 minutes, spooning some broth over the tops once or twice along the way.
Lift the meatballs and cabbage into a serving bowl. Stir the remaining 1 tablespoon cornstarch into 2 tablespoons cold water, whisk it into the simmering broth, and cook for about a minute until the sauce lightly coats a spoon. Pour it over the meatballs, scatter with the scallion greens, and serve with rice.