1. For the dough:
Bring water to a boil in a saucepan.
Place the wheat flour in a bowl, then gradually pour the boiling water over it while stirring with a spatula. As soon as the dough starts to stick and form a ball around the spatula, stop adding water.
On a work surface sprinkled with cornstarch, knead the dough until smooth.
Shape into a log, then cut into sections the size of a lime and form balls. Massage each ball with oiled hands to obtain a shiny appearance.
Using a rolling pin, flatten the balls into discs, adding oil to the work surface if necessary.
Cover as you go to prevent the dough from drying out.
2. For the filling:
Finely chop the scallion.
Finely chop the shrimp and bamboo shoots, then place them in a bowl. Season with mirin, chili sauce, sesame oil, and salt, then add the chopped scallion.
Place a spoonful of filling in the center of a disc, then pinch the edges of the disc to create a 0.5 cm hem, forming a pleated crescent.
Place parchment paper on the steamer basket, steam for 4 minutes, and serve immediately.