Toss shredded cabbage with salt in a large bowl. Let sit for 10 minutes, then squeeze out excess liquid with your hands or through a clean kitchen towel.
In a large mixing bowl, combine ground pork, drained cabbage, soy sauce, sesame oil, rice wine, grated ginger, chopped green onions, and black pepper. Mix thoroughly until well combined.
Place 1 tablespoon of filling in the center of each dumpling wrapper. Lightly moisten the edges with water, fold the wrapper in half, and crimp pleats to seal tightly.
Heat vegetable oil in a large skillet over medium-high heat. Place dumplings flat-side down in the pan and cook until bottoms are golden brown, about 2-3 minutes.
Add water to the pan, immediately cover with a lid, and reduce heat to medium. Simmer for 6-7 minutes until dumplings are cooked through and water has evaporated.