In a large bowl, combine the shrimp, napa cabbage, green onions, garlic, ginger, soy sauce, sesame oil, cornstarch, salt, and pepper. Mix until well combined.
Take a dumpling wrapper and place about 1 tablespoon of the shrimp mixture in the center. Dip your finger in water and moisten the edges of the wrapper.
Fold the wrapper in half to create a half-moon shape, pressing the edges to seal. Repeat with the remaining wrappers and filling.
Bring a large pot of water to a boil. Carefully add the dumplings in batches, making sure not to overcrowd the pot.
Cook for about 4-6 minutes, or until the dumplings float to the top and are cooked through.
Using a slotted spoon, remove the dumplings and place them on a plate. Serve warm with soy sauce or your favorite dipping sauce.