Braise onions, celery and bell pepper in 2 tablespoons oil. In separate pot mix 4 tablespoons oil with the flour to make a roux (brown). Add water, bay leaves, catsup, garlic, file, red and black pepper, Worcestershire sauce and Tabasco sauce to vegetable mixture. Salt to taste. Cook slowly until vegetables are done and flavors well blended. Add okra, tomatoes or sauce, shrimp and crab meat. Thicken with the roux and simmer briefly, adding water as needed until seafood is done. Serve over a bed of steaming rice.