A little slice of Mexico across the street from the Miami-Dade County Medical Examiner. Not that that has any significance, other than Los Tres Amigos certainly has been a welcome addition to the lunch possibilities for all the hard-working medical types in the Jackson Memorial Hospital area. Tres Amigos is the kind of place you virtually never see in Miami: It really looks Mexican inside, Selena plays on the jukebox, and the food really is Mexican/Tex-Mex. You can order the usual varieties of burritos -- chicken, beef, refried beans and cheese -- as well as the superdeluxe burrito Los Tres Amigos, a fat package of beef, pork, and chicken. The best part is ladling on the red or green sauce, or both.