Years ago while living in a tiny High Rise apartment in Japan I used flower pots to grow lettuce in, along with a few other things like carrots. Growing cold crops in window sills is pretty easy to do. I confess I did this before anyone had a chance to tell me that I couldn't or it was stupid. A friend also told me not to pick the lettuce, just pick a few leaves from each plant and it would keep growing.
I learned a few years ago that you could take stuff you buy at the store and cut off the root ends and plant them and they would regrow. Green onions are the easiest to do so you could try those first. Just cut about 1/2 to 1 inch above the roots and plant it. I keep a window box full of them growing all winter long. You can grow these same ones up to 5 times. Romaine lettuce and celery are other ones you could try.
I usual start these seeds in August in their container in the garden area. That gives them time to get going good before we'll need them late autumn. You can start seeds inside later but they seem to start much slower inside in the winter. The ones we start from roots we bought at the store can be started any time.
It's a good skill to learn in cause we ever go through a time we can't get fresh produce. We appreciate it during the winter when the roads are bad and we just want to stay put. I also keep milk in the freezer to be used when we can't get out.
I hope today's tip will help you enjoy free fresh produce this winter!