4 (1 1/2-lb) live lobsters
1/4 cup finely chopped shallot
(1 large) 3 tablespoons fresh lemon juice
1/3 cup mayonnaise
2 tablespoons finely chopped fresh tarragon
Accompaniment (optional): hot dog buns (preferably top-split), buttered and grilled or toasted if desired
Plunge 2 live lobsters headfirst into an 8-quart pot of boiling salted water. Loosely cover pot and cook lobsters over moderately high heat 9 minutes from time they enter water, then transfer with tongs to sink to cool.
Return water to a boil and cook remaining 2 lobsters in same manner.
While lobsters are cooking, combine shallot, lemon juice, and 1/2 teaspoon salt in a large bowl and let stand at room temperature 30 minutes.
When lobsters are cool, remove meat from claws, joints, and tails. Discard tomalley, any roe, and shells (or save for another use). Cut meat into 1/2-inch pieces.
Whisk mayonnaise, tarragon, and 1/4 teaspoon black pepper into shallot mixture. Add lobster meat and toss gently to coat.