In a large sauté pan, melt butter over medium-high heat. Add shallots, onion and garlic and cook, stirring often, until soft, about three minutes. Add flour and cook for 2 minutes, stirring constantly.
Add tomato paste and cook one more minute. Add the wine and sherry and cook 3-4 minutes. Whisk in the cream, lemon juice, salt, and Creole seasoning and cook for 6-7 more minutes. Stir often to prevent sticking. Add crawfish tails and cook until warmed through, 2 to 3 minutes.
Sprinkle with the green onions and parsley just before serving.
Serve with French bread croutons for dipping.
Yield: 1 quart