If you are not using a pressure cooker to cook the sticky rice, you need to soak the rice for at least 6 hours or overnight, otherwise no soaking necessary and just rinse the rice with water. Discard soaking water after that
Soak the shiitake mushrooms in warm water for 30 minutes. Soak the dried shrimp in warm water for 30 minutes too. Save 1 1/4 cup soaking water from soaking the mushrooms. Top up with water if needed. Remove stems from mushrooms and dice into little pieces. Do the same for the dried shrimp
Cook the sticky rice filling:
Preheat cooking oil on a large pan or wok over medium heat. Add garlic and saute for about 30 seconds. Add the dried shrimp, mushrooms, and sausage. Saute for about 5 minutes. Add sticky rice and seasonings. Stir to mix. Turn off the heat
If cooking sticky rice filling with Instant pot pressure cooker:
Transfer the sticky rice filling into a dish (stainless steel or aluminum is best) that will fit into your Instant Pot. Pour the mushroom liquid + water into the sticky rice mixture. Use a spoon to push the rice down to make sure it's covered by liquid. Set a trivet inside the insert of Instant Pot. Set the dish on top
Close the lid and turn the steam release valve to seal. Press "pressure cooker" and "high pressure". Pressure cook on high for 30 minutes. Wait 5 minutes and then release pressure completely
If cooking sticky rice filling on the stove:
Transfer the sticky rice filling into a dish (stainless steel or aluminum is best) that will fit into your steamer. Pour the mushroom liquid + water into the sticky rice mixture. Use a spoon to push the rice down to make sure it's covered by liquid. Steam on high heat for 30 minutes or until the sticky rice is soft
Wrapping:
Place the sticky rice filling on the middle of the wrapper and gather the sides around the filling. Use your thumb and index finger to wrap around the dumplings on one hand and use a spoon to press the filling into the wrapper and top up with more to fill it up
While still holding the dumpling, place it on a flat surface to flatten the bottom so it can "sit" and thumb and index fingers to shape the dumpling into shu mai shape. Make sure there is enough portion of sticky rice in the dumplings because it helps the wrapper to adhere to the filling
Continue until you run out of filling. Brush the bottom lightly with some oil and place in a bamboo steamer or a dish and steam on high heat for 8-10 minutes