In a large bowl, mix together the pork, garlic, ginger, oyster sauce, soy sauce, and black pepper just until combined. Mix in cabbage.
Line a large baking sheet with parchment. Fill a small bowl with water. Remove the dumplings from the package and cover with a lightly damp cloth on work surface.
Lightly moisten the edges of a dumpling wrapper with water, then flip over so the dry side is up. Spread about 1 heaping teaspoon evenly over the surface of the wrapper.
Either place the wrapper in the palm of your non-dominent hand or evenly across the circle made from putting the tips of your thumb and forefinger together. Use a knife or your spoon to press the edges of the wrapper towards the center around the circle, leaving the top of the dumpling open. Tighten your forefinger and thumb around the sides of the dumpling to seal and form a tulip shape.
Use the back of a spoon to smooth out the top of the meat filling. Place on the parchment lined baking sheet and repeat with remaining wrappers and filling. Arrange on the baking sheet in a single layer, without touching.