In a medium bowl, combine the sausage, green onions, soy sauce, hoisin sauce, and garlic. Place 8 wonton wrappers on a clean surface and brush edges with water. Place 1 tablespoon of pork mixture in center of each wrapper. Gather edges of wrapper together over filling. Press edges of wrapper together, enclosing the filling completely. Repeat with remaining wrappers and filling.
Place a collapsible metal steamer rack in a large wide pot. Fill pot with 1/2-inch water. Spray steamer rack with nonstick spray. Bring water to a simmer. Working in batches, arrange dumplings on rack 1-inch apart. Cover pot with lid and steam dumplings until cooked thoroughly, about 8 minutes. Watch the water level and add more as needed. Transfer dumplings to a platter and serve with dipping sauces.