My personal go-to here is "dump a can of beans, and anything you'd like to eat with a can of beans, into a bowl, add a small amount of some sauce, and eat it". :^) I usually use black beans, sometimes garbanzos. Beans and corn (TJ's canned sweet corn is especially delicious) and salsa was my first stab at this; these days, I sautee a couple of packages of sliced mushrooms and toss them in the fridge, and add a handful of those. I'll also often throw in whatever leftover already-cooked veggies we have lying around, like roasted carrots or broccoli. Other good sauces include TJ's Thai yellow curry, TJ's Thai red curry, or any BBQ sauce. I also sometimes sprinkle a Penzeys seasoning blend over it, like Chicago or Mural; oh, or TJ's chili lime seasoning.

TL;DR: Canned beans + veggies that you previously cooked in bulk and then stored in the fridge + some jar sauce or pre-mixed seasoning + a minute or two in the microwave = about 5 - 10 min total prep time.