Finely dice the onion, celery, and carrot to create a consistent base for the bisque.
Melt the ghee in a medium pot over medium heat and sauté the diced vegetables until soft and translucent.
Stir in the tomato paste and dried thyme, cooking for 2 minutes until the paste darkens slightly and becomes fragrant.
Pour in the dry sherry to deglaze the pan, using a wooden spoon to scrape up any flavorful browned bits from the bottom.
Add the seafood stock and bring the mixture to a gentle simmer for 10 minutes to allow the flavors to meld.
Use an immersion blender to process the soup until it is completely smooth and reaches a velvety consistency.
Lower the heat to medium-low and stir in the heavy cream and cooked lobster meat, heating through for 3 minutes without boiling.
Season the bisque with sea salt and black pepper, then garnish with finely chopped fresh chives before serving immediately.