Ingredients Showcase: Soak glutinous rice in water for 2-3 hours in advance. Separate the dumpling wrappers into stacks and roll each stack thinner. Steam the glutinous rice using a steamer cloth until cooked, then break it apart. Dice the sausage and shiitake mushrooms, then mix them evenly with the glutinous rice. Incorporate butter while the mixture is still hot.
Prepare the sauce by combining oyster sauce, soy sauce, and salt. Add a generous amount of black pepper and white pepper. Taste the glutinous rice mixture at this stage and adjust the seasoning as needed. Assemble the shaomai and steam them. Steam over boiling water for 15-20 minutes.