Preheat the oven to 450 degrees F. Line a baking sheet with parchment and coat with cooking spray.
Add the coleslaw to a large microwave-safe bowl. Pour in 1/4 cup water, cover and cook on high until tender and translucent, about 7 minutes. Let cool slightly.
Add the pork, ginger, vinegar, soy, garlic, egg, all but 1 tablespoon of the scallions, 1/2 teaspoon salt and a few grinds of pepper to the coleslaw mix. Mix with your hands until just combined. Scoop mounds of the meat mixture (about 2 tablespoons each) onto the prepared baking sheet. With damp hands, roll the mounds into balls and space them evenly apart on the baking sheet. Bake until cooked through, 12 to 14 minutes.
Put 3 meatballs on each lettuce leaf, sprinkle with the reserved scallions and drizzle with garlic chili sauce. To eat, fold each leaf like a taco and dip into the ponzu sauce.