Assume you had access to a 6 by 6 balcony that faces south with a nice railing and (miraculously) endless access to water. Set whatever budget makes it interesting for you. How would you design your garden to produce as much food as possible? Could you produce enough to sustain yourself? How close could you get? What crops would you prioritize?
I like an herb garden. Basil, cilantro, oregano, thyme. It can all fit in a small space, so there’s room on the patio for more.