In a bowl, combine flour and cornstarch. Gradually add water and knead until you get a smooth dough.
Let the dough rest for 30 minutes.
Roll the dough out thinly and cut into small circles. Sprinkle a little cornstarch on each circle.
In a bowl, mix chopped shrimp, ground pork, garlic, soy sauce, oyster sauce, salt, sugar, and sesame oil.
Optionally, add finely chopped green onions and mix well.
Place a teaspoon of filling in the center of each dough circle.
Gather the edges of the dough to the top, pleating and pressing to seal.
Line the bottom of a steamer basket with parchment paper or lightly oil it.
Place the dim sum in the steamer basket, cover, and steam over boiling water for about 10-12 minutes.
Enjoy your meal!