Enchilada Sauce for Canning

45-50 cups tomatoes, chopped
2 1/2 tablespoons garlic salt
1 1/3 cups chili powder
2 tablespoons salt
7 tablespoons sugar
1 3/4 cups oil
1 1/3 cups flour

Place the tomatoes in a large non-reactive pan (stainless steel or enamel). Heat gently to soften tomatoes. Run through food mill fitted with fine screen to remove seeds and skins.
Return pulp and juice to the pan. If the tomatoes are juicy, simmer the sauce for atleast 1 hour. When you have a thick tomato juice, but not yet tomato sauce, add the garlic salt, salt, sugar and chili powder. Stir well.
In a separate pan heat oil and add flour to make a roux. Blend 4 cups warm tomato juice to roux and mix well. Quickly stir roux paste into boiling tomato juice. Continue stirring to avoid lumps until mixture thickens. If too thick, add water until desired consistency is reached. Adjust seasonings. Ladle into hot jars and process 30 minutes in a water-bath canner.