Heat butter over medium heat. Add flour; stir until dark brown. Add lobster shell, celery, carrots, onion and garlic; simmer over medium heat until wilted. Add sherry, cream and lobster stock (water, lobster base, pepper and tomato paste - previously mixed).
Bring to a boil; lower heat, and simmer for 30 minutes. Stir continuously through entire process and never allow scorching. Remove from heat. Strain.Makes 4 Source: