It's easy to call the bacalao ($8.95), or salt cod, served at Tex Chick [712 1/2 Fairview, (713)528-4708] the best in town, because it's the only one in town. Tex Chick is also the only Puerto Rican restaurant in Houston -- at least the only one we know of. Labeling it a restaurant may be a bit generous, though. The place is so small, it's more like eating in someone's kitchen. Salting as a means of preserving food dates back to prehistoric times. Here the curing process means that the bacalao has an intensely fishy smell, a somewhat salty taste and a texture not unlike calamari. That's enough to put off people unfamiliar with it; however, this flaky fish dish is popular in most Mediterranean countries and in the Caribbean. Here it is served with Spanish rice made with a sofrito (onions, garlic and bell pepper), habichuelas (kidney beans), lettuce and tomatoes.