Turning Roux into Gumbo

By the time you've finished reading the last two posts, you should be fully equipped to rush out and buy enough seafood to make your own New Orleans-style gumbo.

At least, that is my hope. But first, to finish this business of roux.

I was intrigued to read Paul Prudhomme's comment that dark and even "black" roux are "best to use in gumbos because the darkest roux result in the thinnest, best-tasting gumbos of all."

Everyone is familiar with roux as a thickener in the French bechamel sauce: First create a roux by cooking equal amounts of flour and oil (possibly butter) until the flour loses its raw flavor. Then add milk. Creole and Cajun cooking take roux to a whole other level, toasting the flour to various shades of brown or almost black to impart flavor and color, along with thickening the sauce or stew.

What puzzled me was Prudhomme's observation that the darkest roux are not only the best-tasting, but also the thinnest. Being enormous of girth, Prudhomme may have a special affinity for thin roux just on general principles. But there's more to it than that. My own experiences with gumbo correspond to Prudhomme's: No matter how much flour and oil I mix, the darker I cook it, the thinner my gumbo gets.

What's that about?

I thought this question merited a scientific explanation. So I cracked open my copy of Harold McGee's On Food and Cooking: The Science and Lore of the Kitchen (completely revised and updated version). Under "roux," McGee not only observes that darker roux impart a toasty flavor, he goes on to explain why the darkest roux make the thinnest gumbos.

Heating for long periods, McGee says, causes some of the starch chains in the flour to split, then form new bonds with each other. "This generally means that long chains and branches are broken down into smaller pieces that then form short branches on other molecules. The short, branched molecules are less efficient at thickening liquids than the long chains..."

McGee continues, "The darker the roux, the more starch chains are modified in this way, and so the more roux is required to create a given thickness. It takes more of a dark brown roux than a light one to thicken a given amount of liquid."

Hence, rule #1 for gumbo: Make a dark roux for seafood, but don't expect it to be particularly thick. The darker you make it, the more flour and oil you'll need to thicken it.

Having read virtually all of the gumbo recipes in my library, I have the sense that thickness is a matter of personal preference where gumbo is concerned. To make a gumbo for 10 persons, I've seen recipes that call for as little as a few tablespoons of roux, as in original Creole versions, to two cups of roux (meaning one cup oil, one cup flour) or more in various Cajun versions.

I think Prudhomme's recipe is close to optimal. In his version of a seafood gumbo with Andouille sausage he calls for 1 1/2 cups dark roux (3/4 cup oil, 3/4 cup flour) to feed 10 persons. I would procede as follows:

In a heavy stew pot or Dutch oven, bring 3/4-cup canola oil to almost smoking over moderately high heat. Reduce heat to moderately low and slowly stir in 3/4-cup all-purpose flour and cook, stirring frequently until the roux is a dark brown. This could take an hour, so:

While keeping one eye on the roux, shell and devein 1 pound medium U.S. shrimp, either wild-caught or farmed, reserving the shells. Refrigerate the shrimp. Place the shells and 5 cups water in a pot. Bring to a boil and cook, partially covered, for about 20 minutes.

While the shrimp stock is cooking, cut into small dice one large yellow onion, three stalks celery and two green bell peppers. Peel and finely chop 5 garlic cloves. Set aside.

Cut 1 pound boneless, skinless chicken thighs (prefereably pasture-raised) into bite-sized pieces. Refrigerate.

Cut 1 pound Andouille sausage or Kielbasa into bite-sized pieces. Set aside.

When the roux has reached the desired color, the onion, celery, green bell pepper and garlic normally would be added and cooked in the roux until tender. I'm not sure if the roux picks up added flavor this way, or if this method simply avoids messing another pot. I favor cooking the vegetables in a separate pan with a splash of canola oil and some salt, then adding the cooked vegetables to the roux.

While the roux and vegetable mixture is hot, pour the finished shrimp stock into the pot through a strainer and stir to blend. Add the sausage, the chicken, 2 bay leaves, 1/2 cup chopped parsley and 1/2 teaspoon dried thyme at this point. Season with salt (about 1 teaspoon) and freshly ground black pepper to taste. Cook for about 30 minutes, or until quite flavorful. If more liquid is needed, add chicken stock or seafood stock.

The gumbo can be made to this point and refrigerated a day or two ahead. (If you find a layer of oil at the top of the mix, skim it off.) Just before serving, heat the gumbo until it begins to bubble, then add the peeled shrimp and 1 pound of crab backfin meat. Cook another minute or two, or until the shrimp are cooked through.

To serve, distribute cooked brown basmati rice in shallow bowls and ladle generous portions of gumbo over the rice. Hearty greens, well cooked and seasoned with red wine vinegar, can be spooned into the bowl as a side.

Serve with French bread and a nice Beaujolais wine.