- 24 live blue crabs
 - two 3-ounce packets Zatarain's crab boil or 5 tablespoons Old Bay seasoning
 - 1 tablespoon cayenne
 - 1/2 cup table salt
 - 3 lemons, quartered
 - 2 onions, halved
 - 1 1/2 pounds small potatoes (about 2 inches in diameter)
 - 2 heads of garlic (not separated into cloves)
 - 6 ears of corn, shucked
 - 2 tablespoons Old Bay Seasoning, or to taste, for sprinkling over boiled seafood
 - 2 pounds large shrimp (about 30, preferably with heads)
 - Accompaniments:Horseradish Cocktail Sauce and French bread
 
- In a 7- to 8-gallon kettle bring 5 gallons water to a boil.
 - While water is coming to a boil, in a deep sink rinse crabs in 2 or 3 changes of water. (Do not fill sink too full or crabs may crawl out.)
 - Add Zatarain's crab boil or 5 tablespoons Old Bay seasoning, cayenne, salt, lemons, and onions to boiling water and boil 5 minutes. Add potatoes and garlic and boil until tender, about 15 minutes. Transfer potatoes and garlic with a large sieve to a large platter and keep warm, covered with foil. Add corn to boiling water and cook until tender, about 5 minutes. Transfer corn with tongs to platter and keep warm, covered with foil.
 - Return water to a boil. Transfer about 6 crabs carefully with long tongs to sieve, holding them down in sieve with tongs, and turn crabs out into boiling water. Add remaining crabs in same manner. Return water to a boil and cook crabs until just cooked through, about 10 minutes. (To determine doneness, remove a claw and crack it with the handle of a dinner knife. Use Knife to extract meat from claw.) Transfer crabs with sieve to another large platter and sprinkle with 1 tablespoon Old Bay seasoning.
 - Return water to boil and cook shrimp until just cooked through, about 2 minutes. Transfer shrimp with sieve to large platter with crabs and sprinkle with remaining tablespoon Old Bay seasoning.
 - Serve crabs, shrimp, and vegetables with horseradish cocktail sauce and French bread.