It’s not a full meal, but miso soup is a super easy side to anything else you’re making. Get some instant dashi powder and mix it with water, bring it up to a heavy simmer/low boil, turn the heat off, then add in a slurry of miso and water (the slurry should keep the miso from clumping) and mix it in. Then add some cubed soft tofu and chopped green onions (and/or whatever else you want) and you’re done.
Learning to roast vegetables is also easy, cheap, and delicious. The roasting takes a while but the prep work is quick and easy. I especially love Brussels sprouts seasoned with paprika and finished with a bit of balsamic vinegar
9 to 5 maybe?