Mexican Seafood Cocktail

1 1/2 cups chilled Clamato juice, or 1 cup tomato juice and 1/2 cup bottled clam juice
1/4 cup ketchup
1/4 cup fresh lime juice
1 teaspon hot sauce such as Tobasco
1 teaspoon salt
1/2 cup finely chopped white onion
1/4 cup chopped fresh cilantro
1 firm ripe avocado
1/2 lb fresh lump crab meat (1 cup) picked over
1/4 lb cooked baby shrimp

Accompaniment: oyster crackers or saltines (optional)

Stir together Clamato juice, ketchup, lime juice, hot sauce, salt, onion, and cilantro in a large bowl, then gently stir in diced avocado, the crabmeat, and shrimp. Spoon in 6-8 oz glasses or cups.