Crab Cocktail

A cocktail sauce with crab folded through it, in the style of the shrimp and oyster cocktails that opened dinners between the wars. The proportions are unusually sharp by current taste, which is the first thing to address.

• The lemon is the hingeHalf a cup of lemon juice to a quarter cup of catsup makes a thin, aggressively acidic sauce rather than the thick red cocktail sauce most people expect. Start with about 2 tablespoons of juice, taste, and work up if you want the original's bite.
• Heat levelA full teaspoon of Tabasco in a sauce this size is hot by modern standards. Add a few dashes and adjust.
• Crab meatUse cooked lump or backfin crab, fresh or pasteurised from the refrigerated case. Pick it over for shell and cartilage, and fold rather than stir so the lumps survive. Canned crab works but should be drained well and pressed lightly.
• Grated horseradishThe recipe means fresh grated root or the plain bottled kind packed in vinegar, not prepared horseradish sauce with cream or mayonnaise in it. Drain bottled horseradish before measuring.
• Ten minutes is not long enoughThe dressing needs time for the onion and horseradish to soften into it. Mix the sauce and chill it at least an hour, then combine with the cold crab shortly before serving so the acid does not break down the meat.
• ServingSix servings means roughly a quarter cup of crab each, which is a small first course. Serve in stemmed glasses or shallow cups set on crushed ice, with lemon wedges and crackers.
• Make-ahead limitDressed crab holds no more than an hour or two in the refrigerator before it turns watery and the texture goes soft. Dress it at the last minute if you are cooking ahead.