You can easily make enchilada sauce at home with a hot pan and a blender. Vary the spice level and the variety of spice to you own tastes. This recipe is fairly mild.
1 tablespoon oil (I used corn oil)
1 large onion, diced
1 large jalapeño, finely diced, seeds and ribs removed for mild spice
2 large cloves garlic, chopped
2 16 oz cans diced tomatoes
2 teaspoons salt
1/2 teaspoon black pepper
2 teaspoons ground coriander
2 teaspoons ground cumin
2 teaspoons chili powder
1/2 cup chopped cilantro
Heat a pan to medium high heat. Add oil and allow to get hot. Add onions, sprinkle with salt. Stir occasionally, cooking about 8 minutes. Add jalapeños and continue cooking about 5 minutes. Add garlic and cook another 3 minutes.
Add tomatoes and all spices except for cilantro. After 5 minutes, reduce heat to medium and cover. Allow to simmer, stirring frequently for 15-20 minutes.
Remove from heat and stir in cilantro.
You can put the mixture directly into the blender, but I like to let it cool for about 10 minutes. Purée in the blender until you reach a smooth consistency.