Combine chicken broth, garlic, and onion in saucepan. Cook until soft. Add flour, cornstarch, 14 oz chicken broth, and chiles. Stir with whisk until bubbly and smooth. Add flour mixed with water if a thicker sauce is desired. Add seasonings and chicken. Remove from heat.
Combine stewed tomatoes, relish, sour cream, and ½ of cheese in a bowl. In a large bowl, combine goth sauces together.
Make enchiladas by spooning chicken sauce mixture onto each flour tortilla. Roll then up and place in a greased baking dish. Pour the rest of the chicken sauce over the rolled up tortilla and sprinkle remaining cheese on top.
Heat at 350° for 15-20 minutes or until hot and bubbly.