For the beef: Put the garlic and onions into a 6-quart slow cooker. Place the brisket on top. Sprinkle over the ancho powder and 1 teaspoon each salt and pepper. Pour in the enchilada sauce. Cover and cook on low until the meat falls apart, about 8 hours.
For the tortillas: Meanwhile, preheat the oven to 350 degrees F. Wrap the corn tortillas and flour tortillas in foil and warm them in the oven for 15 minutes. Serve the meat with the tortillas as part of a taco bar.
Avocado Lime Crema:
Add the avocados, cilantro, sour cream, milk, salt, pepper and lime zest and juice to a blender. Blend until smooth. Serve as part of a taco bar.
Basic Brown Beans:
Add the beans, chili powder, 1 1/2 teaspoons salt and 2 teaspoons pepper to a large pot. Add cold water to cover by 2 inches. Bring to the boil, reduce the heat and simmer, covered, until tender, about 6 hours. Serve as part of a taco bar.
Grilled Mini Peppers:
Heat up a grill pan and slap the peppers on. Cook, turning them occasionally, until blistered on all sides and softened, about 8 minutes total. Remove and set aside. Serve as part of a taco bar.
Mango de Gallo:
Add the jalapenos, tomatoes, onions, mangoes, cilantro, lime juice and salt to a bowl and stir together. Serve as a taco bar fixing.
In a blender or food processor (see Cook's Note), combine the diced tomatoes, whole tomatoes, cilantro, onions, garlic, chiles, hot sauce, cumin, salt, sugar and lime juice. Pulse until you get the salsa to the consistency you like; I do about 10 to 15 pulses. Test seasonings with a tortilla chip, if you dare. Refrigerate for at least an hour before serving.
I recommend using a 12-cup food processor, as this recipe makes a large quantity. Alternatively, you can blend or process the ingredients in batches and then mix everything together in a large mixing bowl.