Sweet Potato Enchiladas

3 medium sweet potatoes (about one pound)
3 tablespoons butter
2 medium onions, diced
3 cloves garlic, minced (about 11/2 teaspoons)
2 teaspoons ground cumin
2 teaspoons fresh oregano (or 1 teaspoon dried)
1 teaspoon ground coriander
1 teaspoon salt
12 corn tortillas
1 recipe enchilada sauce (below, or 4 cups prepared enchilada sauce)
1 cup grated sharp cheddar cheese

Preheat the oven to 350 degrees F. Lightly grease a 9-by-13-inch
backing dish.  Bake the sweet potatoes on a baking sheet until soft,
40 to 50 minutes. Let cool, and then peel and mash.  Melt the butter
in a medium skillet over medium-high heat. Add the onions; saut\xe9
until translucent, 5 to 7 minutes. Stir in the garlic and cook for
1 more minute.  Stir in the cumin, oregano, coriander and salt;
cook stirring constantly, for 2 minutes. Add the mashed sweet
potatoes and cook for 2 minutes longer.  Remove from heat.  Wrap
the tortillas in a dish towel and place in a steamer basket over
boiling water for about 10 minutes.  Fill each tortilla with about
1/3 cup of the sweet potato filling and roll up. Place the filled
tortillas in the prepared baking dish. Pour the sauce over the top
and sprinkle with cheese. Bake until the sauce is bubbling and the
cheese is melted, 20 to 25 minutes.


Enchilada Sauce
                                                                                 
1 tablespoon vegetable oil
1 medium onion, minced
1 tablespoon chili powder
2 teaspoons ground cumin
2 teaspoons fresh oregano (or 1 teaspoon dried)
8 cloves garlic, minced
4 cups pureed tomatoes
Salt to taste

Heat the oil in a medium skillet over medium heat. Add the onion,
chili powder, cumin, and oregano; cook, stirring for 5 minutes.
Stir in the garlic and continue to saut\xe9 until the onion is soft,
2 to 3 more minutes.  Add the tomatoes and a pinch of salt, Cook
over low heat until flavors are fully developed, 30 to 45 minutes.
Season with more salt to taste.