Combine cabbage and 2 teaspoons salt in a large bowl and toss to combine. Transfer to a fine mesh strainer over a bowl and let stand for 15 minutes.

Transfer cabbage to a clean dish towel, gather the edges, and squeeze out excess moisture. Discard liquid.

Combine pork, drained cabbage, remaining teaspoon salt, white pepper, garlic, ginger, scallions, and sugar in a large bowl. Knead and turn until the mixture is homogenous and sticky.

Test the filling by microwaving a teaspoon-sized amount for about 10 seconds. Adjust seasoning if desired.

Set up a work station with a small bowl of water, a clean dish towel for wiping fingers, a bowl with dumpling filling, and a parchment-lined baking sheet for finished dumplings.

To form dumplings, hold one wrapper on your hand. Place 2 teaspoons to 1 tablespoon of filling in the center. Moisten the edge of the wrapper with water and seal by folding into a crescent shape, pleating the edge.

Transfer finished dumplings to the baking sheet. Freeze for at least 30 minutes if storing.

To cook, heat 1 tablespoon of oil in a medium non-stick skillet over medium heat. Add dumplings in a single layer and cook until golden brown, about 1 1/2 minutes.

Increase heat to medium-high, add 1/2 cup water, and cover. Steam for 3 minutes (5 minutes if frozen). Remove lid and continue cooking until water evaporates and dumplings crisp, about 2 minutes.

Slide dumplings onto a plate, crisped-side up, and serve with sauce.

For the sauce, combine vinegar, soy sauce, and chili oil.