There's an entire movement of convenient cooking in vacuum flasks, which generally entails cooking a grain or small legume (like lentils or split peas) or a mixture thereof in a thermos. The equation goes something like this: boiling water + dried ingredients in thermos x a few hours = hot and healthy meal. And as it turns out, the time required is just about equal to the typical stretch between morning prep to lunch break.
Fresh ingredients can be added, but their addition means the whole mixture needs to be brought to a boil ahead of adding to the flask, as their moisture reduces the temperature in the flask by enough to keep the dry ingredients from cooking thoroughly.
We're thinking the easiest use of this method would be a lunch of a grain and lentils with dried herbs and spices. One could keep a jar in the pantry with the ingredients pre-mixed and just dole a bit out each week morning, add boiling water, and head off to work. By the time lunch rolls around, you'll have a hot lentil lunch waiting for you.
Check out these sites for a wealth of further information on thermos cooking:
Related: 10 Terrific Thermoses