MIA food options are shAAmeful. Just spent a long layover enroute south there this past week. The new terminal is nice but the worst food options in North America still remain.
I recommend anorexia or a liquid diet at the Havana Jet Bar located just outside security next to the first class check in. They make a mean mojito. There is also a Mojito bar and Starbucks next to get D36 that is passable.
You can also try some of the food in the Admirals Club but I think the verdict is pretty much out on that stuff.
The Beachcomber cafe at the end of the new terminal (D) looks appealing until you read the menu - conch fritters etc - sounds a bit dicey to be eating at an airport resto.
Good luck!