1. Fill a large pot with 1/2 inch of water. Stir in 2 teaspoons kosher salt and bring the water to a boil. Add the lobster, cover with a tight-fitting lid and return the water to a boil. Once boiling, lower the heat to a gentle boil and cook the lobsters until they are bright red, about 12 minutes.
2. Remove the lobsters, reserving the liquid. When the lobsters have cooled slightly, place them in a bowl and remove the meat from the claws and tail, again reserving any liquid that comes out of the shells. Chop the meat and refrigerate. Roughly chop the shells into small pieces and reserve, along with all the lobster remains.
3. In a pot, Swirl the olive oil, add the vegetables, herbs, tomato paste, vinegar, 4 cups of lobster broth, prawn heads and lobster shell, along with rice and bring to a boil. Half way through add in more broth if needed
4. Once cooked, transfer it to a heavy duty blender and blend. Strain the broth through a colander, pressing down hard on the solids to extrude as much liquid as possible. Repeat the straining process to ensure a smooth consistency.
5. To serve, pour the bisque into a pan and add the cream and bring to a low simmer. Add the chopped lobster meat, let it heat through, then season to taste with salt and cayenne.