Cowpeas for South Florida Summers
From TheFloridaprepper: It's very difficult to grow more traditional vegetables in South Florida in the summer. If you plant Cowpeas in late sping, they can produce for you well into the summer.
Another suggestion from the comments: Everglades Tomatoes seem to grow constantly, does not matter the season here in south Florida. The plants do take up a lot of room however the small tomatoes taste amazing and they are tough low maintenance plants. http://www.localharvest.org/native-florida-wild-everglades-tomato-seeds-C19069