Gosh, there are so many...have you checked Tried and True under the appetizers?
It sounds like you want something that can be served at room temperature or cold? Here is an interesting one, I have not tried it, but it does sound like it would fit the bill. I can vouch for lime cooking the meat.
I have to speak up- can't help it. Luau is Hawaiian. Here are some real dishes to consider
Dole Pineapple sure did a great marketing job back in the 50s convincing everyone that Hawaiian food is full of pineapple....but it isn't. Hawaiian folks eat pineapple but if you want real Hawaiian recipes suitable for luau, go see this list from the old project we did years ago at Gail's. Surprise everyone by bringing a real luau dish. Appetizers in Hawaii are called pupus.