First I slice off the stems of the guajillo, ancho, and arbol chiles, and shake out their seeds. Then I rinse them to clear off any dust. Next, I place them in a pot, cover with water, bring up to a simmer, and let them soften (about 15 minutes).
While the chilies are softening, I roast the Roma tomatoes, quartered white onion, and garlic cloves (unpeeled) under the broiler until they char just a bit, typically 4-6 minutes. This caramelization adds that smoky-sweet depth that transforms the sauce.
I drain the softened chiles (reserving one cup of the chile water) and put them in the blender. Then I add roasted tomatoes, onion, garlic (peeled), beef broth, vinegar, salt, pepper, cumin, Mexican oregano, cloves, cinnamon, and ginger. Blend on high until completely smooth, about 1-2 minutes. That’s the heart of the birria sauce.
Then I place the beef chunks into the slow cooker, pour the sauce over them, tuck in the bay leaves, and stir gently so the meat is coated. I set the cooker to low and let it go for 8-9 hours (or high for 4-5) until the beef is super tender and falling apart.
Once the beef is tender, I remove it and shred it using two forks. Discard the bay leaves. I return the shredded meat into the crockpot, stir well so it soaks up the sauce (consommé), allowing each shred to get flavor and moisture.
Finally, I serve straight from the slow cooker in bowls with the consommé, or use it for tacos (especially quesabirria), nachos, etc. Garnishes like chopped onion, cilantro, and a squeeze of lime finish the dish beautifully.