For the filling: 300 g (2/3 lb) raw shrimp, peeled and deveined
30 g (2 tbsp) pork fat or bacon fat, finely diced (optional but classic)
30 g (1/4 cup) bamboo shoots, finely diced
1 tsp cornstarch
1/2 tsp salt
1/2 tsp sugar
1/4 tsp white pepper
1 tsp sesame oil
For the wrappers: 100 g (3/4 cup) wheat starch (not wheat flour)
40 g (1/3 cup) tapioca starch, plus more for dusting
160 ml (2/3 cup) just-boiled water
2 tsp lard or neutral oil
To serve: soy sauce and chili oil
How to make it
Make the filling (10 min): Pat the shrimp very dry. Chop half into a rough paste and the other half into pea-size pieces. Mix with the pork fat, bamboo shoots, cornstarch, salt, sugar, pepper and sesame oil, stirring hard in one direction for 1 minute until springy. Chill 15 minutes.
Make the dough (5 min): Whisk wheat starch and tapioca starch in a bowl. Pour in the just-boiled water all at once and stir fast with chopsticks; the starch cooks on contact. Cover 2 minutes, then add the lard and knead on a tapioca-dusted board until smooth and glossy. Keep it covered with a damp towel; it dries in minutes.
Roll (15 min): Roll a third of the dough into a rope and cut into 6 to 7 pieces, about 10 g each. Press each flat with the side of an oiled cleaver (or a tortilla press lined with oiled plastic) into a 7 cm (2 3/4 in) circle.
Fill and pleat (25 min): Put a heaping teaspoon of filling in the center. Fold the wrapper in half over it; on the back edge, make 8 to 10 small pleats pressing each onto the smooth front edge, curving it into a crescent. Pinch the top shut.
Steam (6 min): Set on oiled parchment in a bamboo steamer, 2 cm apart. Steam over boiling water for 6 minutes until the wrappers turn clear and you can see pink shrimp through them.
Serve (right away): Har gow toughen as they cool, so eat them hot with soy and a little chili oil.
Tips
Wheat starch is sold in Asian groceries, often labeled 'wheat starch' or 'tang mian'. Flour won't work.
If the dough cracks when you fold it, it's too dry: knead in a few drops of hot water.