Melt the butter in a large saucepan over medium heat. Add the finely chopped green onion and diced celery, sautéing until softened.
Incorporate the sifted flour into the butter and vegetable mixture, ensuring a smooth and well-combined consistency. Cook and stir for approximately 2 minutes to develop a subtle roux.
In a separate saucepan, gently warm the whole milk over medium heat, being cautious not to bring it to a boil. Slowly add the warmed milk to the roux mixture, stirring continuously to prevent lumps. Continue cooking until the mixture thickens to perfection.
Introduce the freshly ground black pepper, high-quality tomato paste, and the sumptuous heavy whipping cream to the thickened mixture. Stir thoroughly to create a velvety, well-seasoned base.
Optionally, for a smoother texture, use a blender or food processor to puree the bisque. Return the mixture to the saucepan.
Gently fold in the premium crab meat, cooked shrimp, and, if desired, the sherry wine. Stir delicately and bring the bisque to a gentle simmer.
Serve this culinary masterpiece immediately, allowing your guests to savor the symphony of flavors.
