For the dumplings: Heat the oil in a large nonstick skillet set over medium-low heat. Add the onions and cook, stirring occasionally, until translucent, about 5 minutes. Add the ginger and garlic and cook, stirring, until softened, about 1 minute.
Add the tofu, increase the heat to high, and cook, stirring constantly, until the tofu is dry and golden, about 5 minutes.
Add the soy sauce and sesame oil and cook until the liquid evaporates. Turn off the heat. Stir in the scallions, cabbage, carrots, cilantro, salt and pepper.
Place the filling in a strainer and cool to handle, 10 to 15 minutes. Squeeze out any excess moisture. Place the mixture in a large bowl, add the egg and mix thoroughly.
Fill a small bowl with cold water. Place a dumpling wrapper in your hand, then spoon 1 tablespoon of the filling into the wrapper. Use your finger to rub water along the edge of the wrapper and fold in half to enclose the filling, pressing the edges to seal tightly. Repeat for the remaining wrappers and filling.
Line a bamboo steamer with cabbage leaves. Arrange the dumplings in a single layer so they are not touching, cover the steamer with a tight-fitting lid and cook over a water bath until the filling is firm and the wrapper is translucent and slightly gummy to the touch, 15 to 20 minutes. Depending on the size of the steamer, you may need to do this in two batches.
For the sauce: Combine some soy sauce with sliced scallions.
Serve the dumplings immediately with the dipping sauce.
Look for dumpling wrappers in the refrigerated section of the supermarket or specialty Asian markets. Thicker is better when choosing dumpling wrappers, the Northern style is preferred, but gyoza wrappers work well too. If you don't have a bamboo steamer, there are other ways to steam the dumplings. Steamer insert for a stock pot: line the bottom of the steamer with cabbage leaves and arrange the dumplings in a single layer, cover the pot with a tight-fitting lid and cook for 15 to 20 minutes. Vegetable steam basket: line the bottom of the steamer with cabbage leaves and arrange the dumplings in a single layer, cover and cook for 15 to 20 minutes. Be sure to line any steaming device with cabbage leaves or oil-brushed parchment paper.
(c) 2014 Turner Broadcasting System, Inc. All rights reserved.