1. Heat the oil in a wok or a large sauté pan. Add the bok choy and saute quickly until wilted. Let cool, then drain and chop finely. Press out any excess liquid and reserve.
2. In a food processor, puree the tofu with the egg whites and add to bok choy along with the scallions.
3. Combine the remaining ingredients, except the gyoza wrappers and add to the bok choy mixture, mixing well.
4. Place about two teaspoons of filling in the center of each gyoza wrapper. Draw dough up and pinch together at three points to form a triangle, leaving middle of filling exposed. Dampen the dough lightly around the edge with a little cold water on the tip of your finger.
5. Arrange on a square of parchment paper and place in the steamer. Steam over boiling water until the dumplings are cooked through, about 4 minutes. Serve with soy sauce or the dipping sauce of your choice.
*How to Use a Bamboo Steamer
Before using for the first time, scrub the bamboo thoroughly with mild soap and water. While it is still wet, steam it for 30 minutes. To cook, place one section of the bamboo steamer in your wok (or snugly over a large pan) so that it fits nicely with some room around for the edges. The steamers can be used with a wok or a saucepan. The basic rule of thumb is that a wok should measure about 2” larger in diameter than a steamer. If you don’t have a wok and want to use a saucepan, you’ll get the best results when they fit together snuggly so that the water drips back into the pan. Add water until it just touches the bottom of the first bamboo layer. Then stack the top section of your bamboo steamer, one on top. Cooking can be done in the top section only. Use a bed of lettuce, aluminum foil or parchment paper to line the steamer bottom. Take care not to cover all of the holes. If you are using a dish, make sure there’s enough room between the dish and the sides to allow the steam to rise. Cover snugly with your bamboo steamer lid, and start the water boiling. Steam food to perfection by taste-testing with a fork, to determine when the food is cooked.
Care & Storage of Bamboo Steamer
Rinse the steamer with water and, if necessary, use some mild soap. Do not put it in the dishwasher. Store in a well-ventilated place.