Toss the shredded cabbage with the potato starch until evenly coated.

In a bowl, combine the ground pork and all ingredients marked as mixture A. Mix until the mixture becomes sticky.

Finely chop the onion and add it to the pork mixture. Mix well.

Shape the meat mixture from step 3 into bite-sized balls. Wrap each ball with the cabbage from step 1, gently pressing to coat.

Arrange the cabbage shumai on a microwave-safe plate, leaving space between each. Loosely cover with plastic wrap and microwave at 600W for 4 minutes.