Gumbo is a spicy, hearty stew or soup, found typically on the Gulf of Mexico in the United States, and is very common in Louisiana among Creoles, Southeast Texas, southern Mississippi and the Lowcountry around Charleston, South Carolina, and down past Brunswick, Georgia. It is eaten year round, but is usually found during the colder months. This is due to the extended cooking time required, as a large pot full of simmering liquid will lose heat to the surrounding area.
Gumbo usually consists of two components, rice and broth, and is usually made in large batches. Left-over broth is frozen for later use. Rice is made fresh daily. The rice is prepared separately from the broth, and the two are mixed only in the serving bowl.
The gumbo broth can contain seafood (typically crab and shrimp from the Gulf of Mexico or crawfish), fowl (usually duck, quail, chicken), and other meats, used as seasoning; tasso (Cajun smoked pork), Cajun-style andouille (smoked sausage), and other smoked or preserved meats. A traditional lenten variety called gumbo z'herbes (from the French gumbo aux herbes), essentially a gumbo of smothered greens thickened with roux, also exists. The one essential ingredient of the dish is okra, as the name gumbo is derived from a West African word for okra.
Charleston gumbo is often beef or seafood based, although the dish can vary extensively, and is often served over rice. The defining characteristics of gumbo are the type of stock used and the thickening agent used.
A second characteristic, though not necessary, is that the ingredients (base, roux, stock, meat, etc.) are cooked separately, then added together and allowed to simmer.
The stock is always as rich as possible, made with whatever complements the type of gumbo (seafood stock for seafood gumbo, chicken stock for chicken gumbo, etc.) This usually means roasting bones with mirepoix in the oven and then simmering in water for several hours.
Common thickening agents used are okra, filé powder and roux. The classic recipes ask for okra or filé powder. Roux may be added to either, and nowadays it is quite common for roux to be the sole thickening agent itself. Okra is the most popular, especially in restaurant kitchens. Mixing okra and filé is uncommon in Louisianan cuisine, as filé was originally an okra substitute when okra was not in season; although some cooks do this.
The traditional practice of using okra in the summer (in season) and filé in the winter has played a role in defining the kinds of gumbo usually associated with each. These associations are not hard and fast rules, but more of a general guide. For example a purely seafood gumbo is usually not thickened with filé, while one that is purely meat and game would usually not have okra. This reflects traditional practices of fishing and crabbing in warmer weather and hunting and butchering in cooler weather.