Place the fish in an ovenproof casserole with the court bouillon and white wine. Bring to a boil. Cover, reduce heat, and simmer for 15 minutes. Transfer the fish to a warmed serving platter and strain the poaching liquid. Set aside 4 cups of the poaching liquid. In a large saucepan melt the butter. Whisk in the flour and cook over low heat for 1-2 minutes. Slowly pour in the reserved poaching liquid and boil hard for 10 minutes, skimming occasionally, until thickened. In a small bowl whisk together the anchovy purÄe and egg yolks. Remove the saucepan from the heat and whisk in the anchovy mixture. Do not allow to boil. Season with salt and pepper. Serve with the fish.
