This creole specialty is a mainstay of New Orleans cuisine. It's a thick, stewlike dish that can have any of many ingredients, including vegetables such as okra, tomatoes and onions, and one or several meats or shellfish such as chicken, sausage, ham, shrimp, crab or oysters. The one thing all good gumbos begin with is a dark roux, which adds an unmistakable, incomparably rich flavor. Okra serves to thicken the mixture, as does filé powder, which must be stirred in just before serving after the pot's off the fire. The famous gumbo z'herbes ("with herbs") was once traditionally served on Good Friday and contains at least seven greens (for good luck) such as spinach, mustard greens, collard greens and so on. The name gumbo is a derivation of the African word for "okra. "