You really can fill wontons with anything. I generally just browse the fridge for ingredients and fill 'em up. Today I had 3 links of italian sausage, 1/2 a large vidalia, goat, brie, and a monterrey jack/cheddar combo.
Chad doesn't like brie, or goat cheese (weirdo, I know.) so he got his own special wontons. Or you could say that i got MY own special wontons, either way we both win. : )
For mine I carmalized the onion in olive oil and butter, spread a little of cheese on the skin (either brie or goat, not together), topped with the onion (I put a little sausage in some of them), put a little water on my finger to run around the edges, folded them up and finally, I fried them.
For Chad's wontons I mixed sausage a little ranch dressing (like a couple Tbs.) and monterrey jack and cheddar cheese together. I put a little in the center of the skin, and like mine folded them up. I fried both in a little canola oil, but the could have been baked as well.
I made quite a few so I ended up freezing them in a single layer on a baking sheet then when frozen I put them in a ziplock. These will be a tasty treat for a later date.