Heat a skillet or Dutch oven over medium heat.

Pour in the oil. When warm, add the flour.

Cook the roux over medium heat until it has darkened to a deep brown color, constantly stirring to ensure the flour does not burn. (There should be no black flecks in the roux. If there are burned bits, you will need to start over because the scorched taste of a burned roux cannot be fixed.)

You may turn down the burner when your roux is a milk chocolate color and continue cooking it until the roux reaches a dark chocolate color. Many people stop cooking their gumbo roux at a milk chocolate color. To get the big, bold, nutty flavor of a true dark roux, you need to keep cooking it until it’s a deep dark chocolate brown. There should not be black flecks in it.

When it’s ready, the roux will be a dark chocolate color. It will smell nutty and toasted. The cooking of the roux will take between 30-45 minutes total, depending on your stovetop.

Remove from the heat, and let cool slightly before adding to a gumbo or storing in the refrigerator for later.