You're limited only by your imagination...(and fuel).
First day, a pre-prepared and frozen meal; wrapped in tinfoil and bubble-wrap it'll be fine for at least a day, longer if you weigh it down in a cool stream with a rock.
Stir-fries and the like are easy. I've made fantastic onion bhajis/veg pakora. As with many dishes, just adapt recipes from home cooking.
Make one dish (e.g. potato curry, simple) while rice steeps in a pot cosy in another pan.
Simple pizzas, using modified bannock bread mixes.
In the past I've used two pans, one inside the other sitting on bits of gravel, plus a bit of water - a simple oven/bain marie. I intend trying out whether I can do that with just one pan, sitting within a loose bag of tinfoil. Don't know if it'll work - but why not have a go?
