If you have Armadillo Rub from Tears of Joy, use that in place of the dry rub. Serves 6-8.
For the dry rub:
1 Tbsp ground ancho chile powder
1 tsp cayenne pepper
1/2 tsp chipotle chili powder
1/2 tsp paprika
1/4 tsp ground cumin
1/4 tsp garlic powder
1/4 tsp onion powder
1/4 tsp kosher salt
1/4 tsp fresh black pepper
For the brisket:
2- to 2-1/2 lb brisket
1 tsp vegetable oil (or other neutral oil: rice bran oil is my current favorite)
1 medium onion, chopped
1 10-oz can of RoTel
2 12-oz bottles of beer, any type (I use O'Doul's nonalcoholic beer)
In a small bowl, combine all of the spices for the rub. Place the meat in a deep-sided dish, and pat the rub onto all sides. (You'll probably have some rub left over, depending on the size of your brisket.) Let it sit for 30 minutes.
In a small frying pan, heat the oil, and sauté the onion over medium heat for 2-3 minutes, until translucent.
Transfer the cooked onion to a 4- or 5-quart slow cooker. Place the brisket on top of the onions, and pour the RoTel and beer over it.
Cover, and cook on LOW for 8 hours, or until the meat is fork-tender. Remove the meat to a casserole dish and tent loosely with aluminum foil. Pour the liquid (there will be chunks of tomato and onion in it, and you definitely want to keep those) into a small saucepan set over high heat, and boil to reduce the juices by one-fourth. Remove from heat and set aside.
When the meat is cool enough to handle, slice it against the grain, and serve with a bit of the reduced sauce on top. Or, cool completely, and freeze.