Melt the ghee in a medium pot over medium heat.
Add the diced yellow onion, celery, and carrot, then sauté until the vegetables are softened and translucent.
Stir in the tomato paste, sea salt, black pepper, and dried thyme, cooking for one minute to allow the flavors to meld.
Pour in the dry sherry to deglaze the pan, using a wooden spoon to scrape up any flavorful bits from the bottom.
Add the seafood stock and bring the liquid to a gentle simmer for 10 minutes to develop the base.
Use an immersion blender to puree the soup until it reaches a completely smooth and creamy consistency.
Stir in the plain Greek yogurt and the lobster meat, heating gently for 3 minutes until the lobster is warmed through.
Ladle the bisque into bowls and garnish with finely chopped fresh chives before serving.