Chopping one onion is hard? That's maybe a minute of work to add a lot of flavor. I don't generally do that for lunch, but I'll absolutely chop up a couple of baby carrots, chop a couple green onions, scramble an egg or two, and mix it in as I fry up some leftover rice. Add some soy sauce, a few spices, and you've got some serious flavor with 5-10 minutes of work.

The hardest part of that is having leftover rice on hand.