I'm from Northern California and live in Miami now. I've been a little grossed out with the produce at Wild Oats, Whole Foods, Homestead farmer Coops and even Epicure - so I did some research and found a fabulous outdoor organic produce market!
Sunday's only. Best to get there at opening time 9am but is open all day.
Beside the most amazing selections of exotic and unusual fruits and vegetables (yellow watermelon, mamey, watermelon radish) there is an amazing variety of mushrooms, many varieties of fresh picked lettuce, AMAZING and I mean the most AMAZING heirloom tomatoes you've ever seen and are to die for - really.
It's called Josh's Organic Garden. They are located at the end of Hollywood Boulevard at the beach on the boardwalk on the SE corner of the big hotel there. You are on the ocean and it's basically on the boardwalk. Can't miss it. It is SO worth the time to find it. There is EVERYTHING you need and it's the freshest and most beautiful produce you will find in ALL of Forida.
An excellent Thai restaurant a building south of the market. Try it if you go later in the day.