In a bowl, mix the dry yeast with the lukewarm water until dissolved. Add the flour and knead until the dough no longer sticks to your fingers. Cover with a damp towel and let rest for 15 minutes.
While the dough rests, prepare the filling by mixing the minced meat with the remaining ingredients until it becomes a sticky paste.
Dust the work surface with flour and divide the dough into 4 equal pieces. Roll each piece into a 2 cm (0.75 in) thick cylinder. Cut each cylinder into 5 equal-length pieces. Flatten each piece into a round disc about 10 cm (4 in) in diameter. Place roughly 1 tablespoon of filling in the center of each disc, then fold the edges up and pinch them together to seal, twisting the top to ensure everything is well sealed.
Line a sieve with a damp cloth and place the dumplings on it. Suspend the sieve over a saucepan filled with water (the water should not touch the dumplings). Cover and steam for 15 minutes.
Serve hot with teriyaki sauce, or chill and serve cold.