Michelle Bernstein does great things with foie gras and I would start at Michy's and/or Sra. Martinez. I also like the Timo dish described above.
I would be amazed if the new DB Bistro Moderne downtown doesn't have a foie gras dish, and almost as amazed if it weren't good (the DB Burger served there comes stuffed with short rib and foie gras - and is also $32). I can't recall having it there, but Le Provencal in Coral Gables has foie, both hot and cold (as a torchon) on the menu. I have had a nice simple torchon of foie gras at La Goulue in Bal Harbour before, but haven't been there for quite a while.
6927 Biscayne Blvd., Miami, FL 33138
Le Provencal Restaurant
266 Miracle Mile, Miami, FL 33134
4000 NE 2nd Ave., Miami, FL 33137
17624 Collins Avenue, Sunny Isles, FL 33160
9700 Collins Ave, Bal Harbour, FL 33154
I don't think DB Bistro has a regular foie gras dish on the menu, although it has the burger and another dish or two that have foie gras in it. I really liked the foie gras dish at Talula, but that is gone. I don't know if they have it at their new place, the Water Club.
210 23rd St, Miami Beach, FL 33139
Foie Gras is my fav. app. I have had it at Timo, Michy's, Prime 112, Azul, and most Recently at Palme D'or. Timo's was served on crostini with caramelized oranges and Michy's was served with waffles and syrup . Palme D'or's was perfectly cooked and was served with a pear balsamic reduction and some really nice veggies . the others were forgettable but i think the 3 i mentioned are more than worthy of a visit for foie and many other things on their menu's.