Last night, we had one of my favorites, bacalao guisado. Guisado is Spanish for stew.
For a picture and recipe, see Rican Recipies. What my mother-in-law makes is very similar to this, except that she serves avocado and panas (both from our finca) on the side instead of tostones, and she used canned tomatoes.
A similar dish is pollo guisado, made with chicken instead of fish, with the addition of potatoes and sometimes bell peppers and a beer. Here's mama's: