Sushi bars and Japanese restaurants everywhere serve a simple sunomono salad of cucumbers and rice vinegar. Garnished with the sweet little precooked bay shrimp sold in the seafood section of most markets, this easy variation on that traditional dish makes a refreshing, light change of pace to more robust outdoor or picnic fare. Serve it as an appetizer or light main course. Kept well-chilled, it travels well, and prolonged marination only improves the flavors and textures. Long, skinny hothouse cucumbers, usually sold shrink-wrapped in plastic, have mild-tasting skins and need no peeling. Keep the sesame seeds separate, to sprinkle on as a garnish at serving time.
