If there is leftover rice in the rice cooker, a fried egg, chili paste and pork fu on that rice is great. Avocado on there is good too. Chili paste on rice if you don't want to make an egg.
A piece of cheese and an apple is good. Apple and peanut butter good. Cheese and crackers good.
I think your best bet, though, is to cook and save a portion you can pop in the microwave when you don't want to cook. And keep something like hummus on hand, healthy and easy. Seasoned canned beans.