For dough: Place the flour in a large mixing bowl. Add the hot water in a steady stream, mixing with a fork until most of the water has been incorporated. If the mixture is dry add a little more water. The dough should be moist but not sticky. Remove the dough from the bowl and knead it on a floured board until it is smooth. Return the dough to the bowl and let it rest, about 5 minutes.
Knead the dough on a floured board, dusting with a little flour to prevent from sticking. Form the dough into a roll about 18 inches long and about 1-inch in diameter. Using a sharp knife cut the roll into 4 equal lengths. Cut each length into 8 pieces to make 36 equal segments. Press each segment with the palm of your hand and roll it into a 3 1/2-inch round. Cover the finished rounds with a damp cloth. Pinch one side of the dough until you have four pleats along the side, and the dough is rounded and shell-like. Place 2 teaspoons of the filling in the center of each round, filling the hollow. Fold the dough over the filling and pinch the two sides together until you have a half-moon dumpling.
To fry: heat the wok and add the peanut oil when the pan is hot. Add the dumplings, pleated edge up, in a single layer, crowding them in wok. Cook until they are lightly brown on the bottoms. Pour in the very hot water, cover tightly, and cook vigorously for 2 minutes. Turn the heat down to a simmer and continue to cook for another 8-10 minutes or until most of the water has evaporated. Uncover the pan and continue cooking until all of the moisture has evaporated and the wok is sizzling again and the dumplings are golden brown and crisp on the bottoms.
To boil: Drop them into a large pot of salted, boiling water for 2 minutes. Remove from the heat and leave them in the water for about 15 minutes. Garnish with green onions.