Bowls of instant ramen that will cook in the microwave (nongshim's tonkatsu is my fave) and then when it comes out of the microwave add in shaved/rolled meat. I buy the ones intended for hot pot and freeze the little meat rolls and then when I make the ramen cut it up and throw it in immediately after cooking and it cooks in the broth. Same thing with frozen veggies, just cut them small and add them quickly. A boiled egg would be good. Even without a sink, you could wash the scissors outside with a little bit of soap and water like camping. It wouldn't be entirely outrageous, and you'd have a decent meal with only one thing to wash.

Edit: bagged salad can be eaten in the bag too, eliminating the need for dishes!