Siu mai or Siomai are steamed dumplings but with an open top. They're just so delicious that every time I go to Chinese restaurants or take out, expect me to order this as an appetizer. My Mom/sis used to prepare this as well and is good served with a dip of soy sauce mixed with any of these: calamansi/lemon/lime/kumquat. Now that I have to make it, there are times I opt out on the water chestnuts since I don't have them but it hardly changes a thing. :D Serving size really depends. Sauce recipe: 1/4 cup soy sauce and 1 tsp lemon or lime or calamansi or kumquat.