Conch or Scallop Cocktail with Avocado

Boca del río, that haven of excellent seafood cooking, sprawls around a little confluence of river mouths including an estuary simply called El Estero. On the bank of the estuary, Isidro Uscanga, a Veracruzan descended from colonial Afro-Cuban ancestors, has a restaurant proudly titled after himself, El Negro del Estero. This is my attempt to re-create one of his various seafood cocktails, justly known as the freshest and best in the area.

Caracol (snail) is what Gulf coast M