That's one of the reasons I've been looking into aquaponics a lot recently. It's a really cool (almost) closed-loop system where fish waste feeds the vegetables. The only inputs are fish food and replacing water lost by evaporation. You get fish and vegetables as outputs.

Insect farming is also another area I'm interested in - you can eat the insects (super nutritious!) and use them as fish food too.

I think our globalized food network is very vulnerable, say to a bad year globally, and the best way to mitigate the risk is to produce as much of your own food as you can.