Combine the flour and oil in a heavy skillet (preferably cast iron or enameled iron) and, with a large metal spatula, stir them to a smooth paste. Place the skillet over the lowest possible heat and, stirring constantly, simmer the roux slowly for 45 minutes to an hour.

After 5 minutes or so, the mixture will begin to foam and this foaming may continue for as long as 10 minutes. After about half an hour, the roux will begin to darken and have a faintly nutty aroma. Continue to cook slowly, stirring with the spatula, until the roux is a dark rich brown. During the last 5 minutes or so of cooking, the roux darkens quickly and you may want to lift the pan from the heat periodically to let it cool. When cooked, immediately scrape the roux into a small bowl. Let the roux cool to room temperature, then cover and refrigerate until ready to use. The roux will keep, refrigerated, for several weeks. Makes approximately 10 TBS.