Chef's tips: Don't skip drying the shrimp – wet shrimp steam instead of char. Salt the cucumber rounds and blot them to prevent sogginess. Store guacamole with plastic wrap pressed directly onto the surface to prevent browning. For make-ahead, cook shrimp and pickled onions up to 24 hours in advance; slice cucumber and assemble just before serving.
Keyword charred shrimp, easy shrimp appetizer, gluten free appetizer, party appetizer, shrimp guacamole bites