Finely chop the onion and mushroom, place in a bowl, and mix in the 3 tablespoons of katakuriko.
Mix well and toss until all the diced pieces of onion separate. If the onion is too moist, add more corn starch and adjust.
Massage the peeled shrimp with salt, then rinse. Chop into a paste.
Combine soy sauce, sake, sugar, oyster sauce, and Chinese soup stock.
Add the pork and shrimp into the bowl from Step 1. Add the mixed condiments from Step 4. Knead well until sticky.
The filling is done when you knead until the meat becomes slightly white.
Spread a shumai skin on the palm of your hand. Place about 25 mm worth of filling on top and wrap it up.
Make a hoop with your thumb and index finger. Place the filled skin on top. Press down into shape.
Spread paper towels in a well-heated steamer. Align the shumai so that they won't stick together. Steam for 15 minutes. Make sure not to burn yourself.
If you are steaming them in a microwave, spread out cabbage or Chinese cabbage leave underneath. It will add moisture and make the shumai extra juicy.
Story Behind this Recipe
It's my vaunted shumai that's been passed on from my mother. It's so authentic that some people even ask me if I bought it in Chinatown, but it's actually easy to make.
The key is to make the onions feel flaky with corn starch. This will help make your shumai moist. Use a steamer if possible. If you're microwaving, spread Chinese cabbage leaves underneath to prevent the skins from drying up. It's well-flavored and shouldn't need soy sauce.