Ingredients

• 6 qt water
• 3 tablespoons fine sea salt
• 4 (1 1/4- to 1 1/2-lb) live lobsters
• 1 stick (1/2 cup) unsalted butter
• 3 tablespoons dry vermouth
• 1 tablespoon tarragon white-wine vinegar
• 3 large egg yolks
• 1/4 teaspoon salt
• 1/4 teaspoon black pepper
• 1/2 teaspoon fresh lemon juice
• 1 1/2 teaspoons chopped fresh tarragon

Instructions

1. Bring water and sea salt to a boil in an 8- to 10-quart pot. Plunge 2 lobsters headfirst into water and cook, covered, over high heat 7 minutes from time lobsters enter water, then transfer with tongs to sink to drain. Return water to a boil and cook remaining 2 lobsters in same manner.
2. Melt butter and cool until just warm.
3. Whisk together vermouth, vinegar, and yolks in a metal bowl, then set bowl over a small saucepan of boiling water and heat mixture, whisking, until warm. Add melted butter in a slow stream, whisking, then whisk in salt and pepper. Cook sauce, whisking, until thickened and registers 160°F on an instant-read thermometer, about 5 minutes. Remove pan from heat and keep bowl in saucepan. Just before serving, stir in lemon juice and tarragon.
4. Working from belly side, halve each lobster lengthwise with a sharp heavy knife or kitchen shears. Serve lobsters with sauce.