I have a Thermos food flask which I take a range of hot meals to work in (no microwave at work). I do make batches of food with veg in such as savoury mince, stew, beef curry, etc. You could leave the veg out but stews and the like are actually a good way of getting some veg without necessarily having to deal with eating separately cooked vegetables.
Carrots, peas, onions all lend themselves well to these kinds of dishes. I hardly eat carbs in my lunches these days so have had to get a bit more inventive as sandwiches do nothing for me.