Toss the cabbage with 1/4 teaspoon salt and let stand for 10 minutes. Add the cilantro, ginger, sesame oil, scallions and garlic and stir to combine.
Fill a small bowl with water. Lay a gyoza wrapper on a work surface and spoon a scant tablespoon of the cabbage mixture into the center. Moisten a finger with water and rub it along the edge of the wrapper. Fold the wrapper over to make a triangle or half-moon shape, then seal with your fingers, trying to push out any air as you go. Repeat with the remaining wrappers and filling.
Heat the oil in a large nonstick skillet over medium-high heat until hot. Arrange the potstickers in the skillet in concentric circles and cook until the bottoms are light golden, about 2 minutes. Carefully add 1/4 cup water to the pan; cover and cook until the liquid has evaporated, the wrapper dough is tender, and the undersides of the potstickers are golden brown, about 6 minutes.
Transfer the potstickers to a serving platter, crispy-side up, and serve with ponzu sauce.