I have plastic versions of this, similar size, set of four. In addition to portioning leftovers directly into them throughout the week, sometimes I'll cook on Sunday and line up my four mugs to fill for the week. One of my favorite go-to's is a made-up vegetarian succotash (I made it up after buying a pre-packaged convenience food in the organics aisle at the grocery and quickly realized I could make my own). I think you could actually just throw the ingredients in the mug raw and use the microwave for cooking, but during the summer this also makes a nice room temperature or even cold salad if you've cooked the mix ahead of time.
Basically all I do is in a big pot, put a mix of diced fresh vegetables and beans (I use rinsed canned beans for convenience), robust flavor olive oil, and a spice mix (whatever I have on hand... I tend to have a lot of little Penzeys blends from gifts). For example: fresh corn cut off the cob, diced red and green peppers, carrots, red onions, with white beans and kidney beans and a French spice blend. Just cook until the veggies are desired texture and transfer to mugs. You could make a Mexican version of this with spicier options and themed seasoning (e.g., poblano peppers, black and pinto beans, etc.). Not vegetarian? Add rotisserie chicken or cooked shrimp or such.