Lobster cappuccino

4 pounds of lobster
2 Tablespoons olive oil
1/2 cup onion, finely chopped
1/2 cup carrot, peeled, finely chopped
2 Tablespoons tomato paste
1/2 cup celery, finely chopped
1/2 cup fennel, finely chopped
1 bay leaf
1 cup tomato, chopped
3 cloves garlic, finely chopped
1 cup cognac
1 cup dry white wine
2 cups milk or heavy cream
3 Tablespoons Xerez Spanish sherry
2 Tablespoons Spanish sherry vinegar
Salt and fresh ground pepper to taste
Foam:
1 cup whole milk
1/4 cup lemongrass, chopped

1. To prepare the foam: Combine milk with lemongrass; bring to a boil and remove from heat. Allow milk to sit for one hour. Strain milk and place in an ice bath.
2. Pour milk into a frother. Test a few times before serving in order to attain desired consistency. For thicker foam, use whipping cream.
3. To prepare the soup: Plunge the lobsters into boiling water for 3-4 minutes. Take lobsters out of the boiling water and remove the tails. Cut the carcasses into quarters, discarding the sacks. Crack the claws. Remove the meat from the tails and set aside.
4. In a large pot, heat oil on medium heat. Saute the lobster shells, carrot, onion, tomato paste and celery. When lightly browned, add fennel, lemongrass, tomato, garlic, bay leaf, and cognac. Cook for 3-4 minutes and add white wine. Add enough cold water to cover at least 3 inches over vegetables. Cook for 45 minutes.
5. Carefully puree soup in batches in a blender on high. Strain pureed soup into another pot with a fine cheesecloth. Add the milk or cream and cook over medium low heat for 15 minutes. Season to taste with salt and pepper. Add dry sherry and sherry vinegar and gently stir.
6. To plate: Chop the tail meat and claws into bite-sized pieces. Place on the bottom of each soup bowl. Pour the hot soup over the lobster. Top with foam.