How To Make Sous Vide Butter-Poached Lobster

Ingredients

• 4 1- to 1 1/2-pound live lobsters (if using 2- to 3-pound lobsters, add 10 minutes cooking time)
• kosher salt
• 1 tablespoon canola or other mild vegetable oil
• 1 yellow onion
• 1 carrot
• 1 fennel bulb or celery stalk
• 3 cloves garlic
• 2 tablespoons tomato paste
• 1 teaspoon black peppercorns
• 1/4 cup water
• Pinch kosher salt
• 1/2 cup cold, unsalted butter
• 1 shallot
• 1/2 cup Cognac, brandy or bourbon
• 1/4 cup dry white wine
• 1 cup creme fraiche
• 1 tablespoon fresh lemon juice
• 1 tablespoon chopped fresh tarragon
• 1 tablespoon minced fresh chives
• salt and freshly ground white pepper