Balilife,
Restaurant business in general takes alot of works, so you have to enjoy working in food business. Be prepared to not make profit in your first 2 years. I could be wrong, but don't think there's a tax break in Indonesia for that potential 2 loss years.
If I do it, I would open up a take-home style cafe in Kuta -- just a "hole in the wall" and put up benches with tables instead of full service table settings. It keeps your up front capital and overhead cost low. I would target mainly the tourists. The candidate list below can be done for breakfast and/or lunch only, so that you can have a family life in the evening.
1) Japanese bento box.
2) Fish chips, and be ready to offer rice and sambal.
3) Donuts and coffee.
4) Take out Chinese barbeque (pork, roast duck, chicken, etc).
5) Not too sure about a burger joint. I think Indonesian tend to eat their burgers from the MickeyD's of the world.
If you decide to open one, let us know. We'll try your food
/hh
No rain, no rainbow.