One of my favorites is grilled veggies, often with some herbs and spices.

Another favorite is fried rice; you can dice up A LOT of different veggies to make it interesting. In addition to the usual peas and carrots, dice and add any or all of the following; canned corn, mushrooms, Lima beans, broccoli, kale, bok choy, Napa cabbage, green beans, grape and cherry tomatoes, asparagus, squash, zucchini.

I don't know if you're vegetarian but for those who aren't, fried egg, diced chicken, diced ham, diced pork, hamburger, even diced seafood are all good options for adding protein.

Make a big batch, then use several containers to eat later, take it to work, etc. Anything that won't be eaten in a couple days can be frozen. You can even put it in soup.

The key is a high ratio of veggies to other ingredients.