Heat oil on medium until hot in a large saucepan. Add the chile powder one tablespoon at a time while whisking constantly until all of the chile powder is dissolved and a paste is formed. Add water as needed to maintain a pasty consistancy. Add the flour & whisk it for 3 to 4 minutes or until the entire mixture thickens. Whisk the water + salt & garlic in.

Simmer the sauce for one hour. Stir occasionally so that it doesn't cake on the bottom of the pan.

From Maria's New Mexican Kitchen in Santa Fe.