Lobsters with Tarragon Vermouth Sauce

Preparation

1. Cook lobsters:

   Step 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. Make sauce while lobsters cook and drain:

   Step 2

   Melt butter and cool until just warm.

   Step 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.

   Step 4

   Working from belly side, halve each lobster lengthwise with a sharp heavy knife or kitchen shears. Serve lobsters with sauce.