Salt the finely chopped cabbage with 1/2 teaspoon salt. Let it sit for 15 minutes, then squeeze out excess moisture using a clean kitchen towel or cheesecloth. This prevents watery filling.
In a large bowl, combine the drained cabbage, ground pork, minced garlic, grated ginger, chopped green onions, soy sauce, sesame oil, and white pepper. Mix thoroughly until well combined.
Place a wrapper on your palm. Add 1 tablespoon of filling to the center. Dip your finger in water and moisten the edges of the wrapper. Fold in half and pleat one side 5-6 times, pressing firmly to seal. Repeat until all filling is used.
Heat 2 tablespoons oil in a large non-stick pan over medium-high heat. Arrange dumplings flat-side down in a single layer. Fry for 2-3 minutes until bottoms are golden brown.
Add 1/2 cup water to the pan and immediately cover with a tight-fitting lid. Steam for 5-6 minutes until water evaporates and wrappers become translucent.
Remove lid and let dumplings fry for another 1-2 minutes until bottoms are crispy again. Serve hot!