Add the garlic, ginger, shrimp and water chestnuts to a food processor and pulse to chop. Add in the soy sauce, oyster sauce, vinegar and pepper and pulse until well combined.
Place about 1 tablespoon of filling in the center of each dumpling wrapper. Wet your finger and moisten the edges of the wrapper. Pinch the wrapper in towards the center, leaving the top of the dumpling exposed. Repeat with the remaining dumplings.
Set a steamer over a pot of simmering water. Place the dumplings about 1 inch apart (you’ll have to cook them in batches) and steam for 8-10 minutes, until the shrimp is cooked through. Serve immediately with dipping sauce of choice.