I've made these a few times now.  I use the pork mince and added red chilies, water chestnuts and garlic.

Love them served with a dip made of soy sauce, rice vinegar and fresh chopped red chilies. 

I've also used up leftover Gyoza wrappers when I ran out of filling (hate to waste anything!), by making a Mexican style mixture with Chorizo, Jalapenos, grated Cheddar Cheese and hot sauce like Frank's; I just fried these ones and didn't bother doing the steaming part as the filling wasn't raw - these were nice too and a fun little fusion experiment.