Not many of us think of a Mexican restaurant when we're hungering for a stuffed crab-back, or salivating over sucking on prawn heads. Perhaps, being stone crab claw and Key West pink shrimp-centric, we haven't had the necessary exposure to inspire such an appetite. Or maybe, being offered mostly central Mexican cuisine here in South Florida, we simply haven't had opportunity enough to appreciate the fact that Mexico has a cuisine derived from its vast stretch of coastline -- and that's just on the Pacific side, where the town of Puerto Vallarta is located. Fortunately our education is at hand via El Puerto de Vallarta, and we're not just talking about the three R's of fish tacos, but the ABC's as well: Avocado-garnished shrimp and snapper ceviche with pico de gallo; botana (appetizers) including shrimp quesadillas and oysters on the half-shell; and seafood caldos (soups), such as the luxurious combination of seven different types of shellfish served with homemade corn tortillas. Finish off your secondary schooling with bacon-wrapped shrimp, or garlic-sauteed lobster and a cool Tecate beer, and you'll be set to graduate.