Julia Child's Homard Gratiné Au Fromage | GBH

Ingredients

• 2 cups dry white vermouth
• 2 cups water
• 1 large onion, thinly sliced
• 1 medium carrot, thinly sliced
• 1 medium celery stalk, thinly sliced
• 6 parsley sprigs
• 1 bay leaf
• 1 tablespoon tarragon
• 2 teaspoons salt
• 1 tablespoon butter
• 4 tablespoons flour
• 1/2 cup heavy cream
• 1/2 cup grated Swiss cheese
• Salt and pepper