Oyster Cocktail II

A single-serving first course from the era when the oyster cocktail was standard American party food. Everything here depends on cold: cold oysters, cold fruit, cold glass or shell.

• YieldThe recipe lists six oysters and cuts a grapefruit into halves crosswise; it does not say how the oysters are divided between the two cups, so treat the yield as one or two servings and scale by the half fruit rather than by weight.
• Grapefruit as vesselCut across the equator, not through the stem, so the segments face up. "Tough portions" means the fibrous core, the white pith and the membrane walls between segments; loosen the segments with a curved grapefruit knife and lift the core out in one piece, leaving a shallow cup of fruit and juice.
• Oyster size"Small" points to something like a petite Pacific or a Kumamoto, roughly two inches. Large oysters are unpleasant to eat whole from a spoon and should be halved if that is all you can get.
• Seasoning proportionsThe original gives none. Two or three drops of Tabasco, a teaspoon of lemon juice and a pinch of salt for six oysters is in the right range. Grapefruit already brings acid and bitterness, so add lemon last and taste.
• Shuck lateOpen the oysters no more than an hour before serving and keep them in their own liquor on ice. Oysters left sitting in acid firm up at the edges, so season them just before they go into the fruit rather than letting them marinate.
• SourcingBuy from a market that can tell you the harvest date and keep the shells cup-down under ice, never in standing water. Raw shellfish carries a real Vibrio risk and should be skipped by anyone pregnant, immunocompromised or with liver disease.
• ServingChill the grapefruit halves thoroughly, and set them in a bed of crushed ice or a shallow bowl so they sit level. A small fork or a bouillon spoon works better than a teaspoon.