Melt the ghee in a medium pot over medium heat until shimmering.
Add the diced onion, celery, and carrot to the pot, sautéing for 5-7 minutes until the vegetables are soft and translucent.
Stir in the tomato paste and dried thyme, cooking for 1 minute to deepen the flavor profile.
Deglaze the pot with the dry sherry, using a wooden spoon to scrape up any browned bits from the bottom.
Pour in the seafood stock and bring the mixture to a gentle simmer for 10 minutes to allow the flavors to meld.
Carefully use an immersion blender to puree the soup base until it is completely smooth and uniform.
Stir in the heavy cream and season the bisque with sea salt and black pepper.
Gently fold in the cooked lobster meat and simmer for an additional 2-3 minutes until the lobster is heated through.
Ladle the bisque into a bowl and garnish with finely chopped fresh chives before serving.