Squeeze the shredded cabbage firmly to remove excess moisture.
Combine pork, cabbage, scallions, garlic, ginger, soy sauce, rice vinegar, sesame oil, sugar, white pepper, and cornstarch.
Set up a wrapping station with wrappers, a small bowl of water, and a sheet pan.
Place a wrapper in your palm and spoon about 1 tablespoon filling in the center.
Moisten the edge, fold into a half-moon, and pleat to seal tightly.
Repeat with remaining wrappers, keeping filled dumplings covered to prevent drying.
Heat 1 tablespoon oil in a large nonstick skillet over medium-high heat.
Arrange potstickers flat-side down. Cook until bottoms turn golden, 2–3 minutes.
Carefully pour in 1/4 cup water. Cover and steam 4–5 minutes until cooked through.
Uncover and let water evaporate. Drizzle a little oil and crisp 1–2 minutes more.
Transfer to a plate and repeat with remaining dumplings, adding oil and water as needed.