On low heat, gradually add flour, stirring constantly with a wooden spoon
8 oz all-purpose flour
For a light roux: cook 2-8 minutesFor a blonde roux: cook 8-20 minutesFor a dark roux: cook 20-60 minutes
Now that the roux is done, add either dairy, broth/stock or water to create the desired sauce; for more info, refer to the post
Notes
Once the roux is cooked, you can gradually add a liquid, (broth, dairy, water) to make a sauce. Make sure you whisk constantly when adding additional liquids or ingredients.