I live in a loft in Downtown LA. Does anyone have any suggestions for a fire escape garden?

Do you have good light? It sounds like you might when you say you're in a loft. With good light you can grow almost anything. All kind of herbs are good.

People grow tomatoes in pots. I recommend cherry tomatoes over full size for home growers. The reason is that farmers charge more for the cherries because they're more work to pick, but if birds and animals get at them they'll eat some of them while the rest will be perfect. With the full size ones, they take a bite out, and you'll find two-thirds of a partly chewed tomato. Less fun. It's great to be able to out and pick a handful for a salad.

You might learn a lot by asking advice from growers at your local farmers markets. They may be able to tell you how the seasons affect particular plants (I know you do have seasons there, even if it's not obvious), about requirements for light and water, etc... They're not probably going to be experts in container growing, but they'll know a lot.