Not because it's sustainable but because what you grow tastes better than anything from the grocery store. The key is intensity: lots of nutrients, sun, heat, and water. The more energy that goes into your garden, the more food that comes out.
1. Build one or more 8' x 4' x 2' raised beds.
Materials (avoid pressure-treated woods, which can leach poisons):
>Four 2" x 12" x 12' planks
>One 4" x 4" x 8' post
>40 or so 4" plastic-coated wood screws
>Two 4' x 8' sheets of 6" x 6" sidewalk remesh
>One clear 6-mil plastic painter's drop cloth
2. Saw 4' off of each of the planks and screw them together, with 2' lengths of the 4x4 at each joint for support.
3. Next, fill the box with the blackest, most nutrient-rich organic dirt you can find. If you need to call in a dump-truck load from a soil yard, each bed should need two cubic yards.
4. Prop the remesh into the beds in an arch shape and cover it with plastic. Bricks, staples, or spare wood all work to pin the plastic in place. You've now got a hoop house on a raised bed that will concentrate and store the sun's energy—and reduce evaporation—for hot-weather plants like squash, herbs, tomatoes, peppers, and melons. Get your tomatoes as starts (spring for the gallon size) and plant the rest as seeds a week before your area's last freeze. My two boxes, one slightly shaded for lettuce and strawberries, produce more veggies than I can eat.