Mix the lobster stock with 4 tblsp of the water, the tomato paste and the sherry, once mixed into a slush add the rest of the water mixing as you add it.
Now over medium/high heat bring to a boil and reduce heat to a simmer and simmer until reduced to 3 cups, about 15 minutes.
Now add the whipping cream and bring to simmer for another 5 minutes. If you have it add the lobster meat and simmer another 3 minutes, otherwise serve.