Dating back to mid-17th-century Spain, the word zarzuela refers to a mixture of song, dance and dialogue -- a sort of variety show. The variety-show concept fits perfectly with the zarzuela de mariscos ($15.50) at Tio Pepe (5213 Cedar, 713-667-4409). It's a casserole, much like French bouillabaisse, prepared with many different kinds of fish. As the theory goes, the more types of seafood, the better the dish. Tio Pepe's thick tomato-based soup, which also includes onions, bell peppers, garlic and wine, is laden with seafood: Scallops, calamari, shrimp, clams, mussels, crab and whitefish all fight for your attention, just like performers on a stage.