In a bowl, combine flour and water, mixing to form a ball. Remove to a floured board and knead with your palm for about 3 minutes. Shape into a ball, cover with a damp towel, and let stand for about 10 minutes.
Make the filling by combining the filling ingredients above. Refrigerate until ready to use.
To shape and assemble, knead dough for about 3 minutes. Roll into a cylinder that is about 1 inch in diameter. Cut off the ends, then cut into about 24 pieces, each about 3/4-inch wide. With the cut side up, press the dough down with your palm to flatten. Use a rolling pin to make pancakes about 2 1/2 - 3 inches in diameter. (They get quite thin; that''s what you want.)
Spoon about 1 tablespoon of filling into the center of each pancake. Fold the dough over to make a half circle and pleat the edges firmly together.
To pan-fry, heat cast-iron or other heavy-bottom skillet over moderate heat. Add about 3 T oil, swirling to coat bottom. (Watch out, it sizzles quite a bit. Don''t get burned!) When oil is hot, place potstickers, seam side up, in skillet and agitate (shake) for 30 seconds. Pour in water, cover and gently boil over moderate heat for 7 to 8 minutes. When oil and water start to sizzle, add remaining 2 T oil. Tip skillet to distribute oil evenly; watch carefully (uncovered) to prevent sticking. When bottoms are brown (usually several minutes later), remove from heat and carefully lift out potstickers with spatula.
To serve, turn potstickers over (dark side up) and arrange on serving platter. Combine chili oil, vinegar and soy sauce in proportions to suit your taste and offer sauce for dipping. Alternatively, cut up a hot chili pepper into red rice vinegar.