Mexican Brisket Tacos with Guajillo and Ancho Chiles

This is a recipe that Cindy gave me and I think it is the most yummy and easy brisket for tacos.  Although the recipe calls for oven, we ended up making it in a crock pot for Cinco De Mayo and Ernesto's 40th b'day and it was so easy!

INGREDIENTS
4 dried New Mexico or guajillo chiles, stemmed and seeded
2 ancho chiles, stemmed and seeded
One 5-pound beef brisket with a layer of fat, cut into 3 pieces (Leave some fat and carve out the rest if needed)
3 tablespoons vegetable oil
1 medium onion, sliced lengthwise; 1/8 inch thick
4 garlic cloves, minced
1 teaspoon cumin seeds
1/4 teaspoon coriander seeds
5 large plum tomatoes (1 1/4 pounds)—cored, seeded and chopped
1 jalapeño, seeded and chopped
One 2-inch cinnamon stick
2 cups chicken stock (I used 1 chicken and 1 vegetable bouillion)
Freshly ground pepper
Salt
Thinly sliced scallions, for garnish

1) In a medium bowl, cover all of the chiles with hot water and let stand for 30 minutes. Drain the chiles and discard the liquid.
2) In a dutch oven, heat 3 tablespoons of vegetable oil. Add garlic and saute till smell is released. Add cumin and coriander seeds and onions. Cook for 3 minutes till onion is translucent.
 ned.
3) Stir in the soaked chiles, chopped tomatoes, jalapeño and cinnamon stick. Sautee until combined for a few minutes.
4) Add meat to crock pot. Dish out sauteed mixture of chillies, tomatoes and onion into the crock post to cover meat. Add broth to cover the meat.
5) Cook for 5 or 6 hours on high.
6) Discard the cinnamon stick. Transfer the meat to a work surface and let cool. Using your fingers, shred the meat.
7) Working in batches, transfer the contents of the casserole to a blender and puree until smooth.
8) Pour the sauce over the shredded meat, toss and serve. It is really delicious and crowd favorite!!

FIXINGS & GARNISH:
Corn Tortillas
Pinto Beans (optional)
Fresh Salsa (Chopped tomatoes, onion, jalapeno, cilantro)
Scallions
Fresh cilantro

MAKE AHEAD: The meat can be refrigerated for up to 5 days or frozen in an airtight container for up to 1 month.