Step 1Mince the shrimp and scallops almost into a paste. Place in a shallow bowl and add the crab, garlic or chives, ginger, sherry, soy sauce, sugar, white pepper and egg white. Mix well.
Step 2To stuff the dumplings, mound about 2 teaspoons of the filling in the center of each wrapper, and brush the outer edges lightly with water to moisten. Fold the wrapper in half, into a half-moon shape, then pinch it together at the center of the top edge. Pleat the edges of the wrapper to enclose the filling. Repeat with the remaining dumplings.
Step 3To pan-fry the dumplings, heat a 10-inch skillet with a lid over medium heat. Add 2 tablespoons of oil and swirl the pan. When the oil is hot, lay 8 to 10 of the dumplings into the pan, leaving room between each, and cook until the bottoms just start to brown, about 2 minutes. Add one-third cup water and reduce the heat to medium-low. Cover the pan and cook until the dumplings are soft on top, crisp on the bottom and the filling is firm, 5 to 7 minutes. Repeat with the remaining dumplings.
Step 4To steam the dumplings, use a steamer of your choice, and bring 1 to 2 inches of water to a simmer (make sure the water level does not reach the bottom of the steamer). Lightly grease the steamer rack, and place the dumplings on the rack about 1 inch apart from one another (the dumplings will need to be cooked in batches). Place the steamer over the simmering water and cover. Steam the dumplings until the filling is firm and the wrapper is slightly translucent, 10 to 15 minutes. Remove the steamer from the water, and gently remove the dumplings to a warm place until all of the dumplings are cooked. Serve warm with a dipping sauce.