In large heavy pot, melt butter and saute onions, celery, green pepper and garlic until soft. Stir in salt, black and cayenne pepper, sugar and tomato paste. Simmer, stirring occasionally, for 20 minutes. Dissolve cornstarch in water; add wine to mixture. Cook for 20 minutes or until sauce thickens. Add crayfish, green onion and Kitchen Bouquet. Refrigerate overnight. Reheat and serve over rice. Don't overcook. Boiling crayfish: Discard any dead crayfish in the sack. Wash crayfish in clean, cool water just before cooking. They do not need to be purged with salt during washing. Place the live crayfish in boiling water and boil for 10 minutes. (Season the water with one pound of salt per five gallons of water. Add other seasoning to taste, including cayenne, garlic, onions, lemons, lemon juice and crab boil.) Don't begin timing cooking until watter returns to a buil after adding crayfish . It's usual to add potatoes and corn on the cob to the boil. Crayfish are easiest to peel when still warm.