Step 1: Prepare the Chilies

1. Place the guajillo and pasilla chilies in a pot and cover them with water. Bring to a boil, then remove from heat and cover. Let the chilies soak for 30 minutes.

Step 2: Roast the Aromatics

2. Heat a pan over medium heat. Roast the onion, garlic, and tomatoes until blackened spots appear. The garlic should finish roasting in about 5 minutes, while the onion and tomatoes will take longer. Rotate for even cooking.

Step 3: Blend the Sauce

3. Transfer the roasted onion and tomatoes to a blender. Peel the garlic cloves and add them to the blender.
4. Add the soaked chilies (discarding the soaking water), vinegar, oregano, thyme, cumin, cloves, cinnamon, peppercorns, chicken bouillon, and 2 cups of fresh water. Blend until smooth.

Step 4: Brown the Meat

5. Season the beef short ribs with salt. Heat a large pot over medium heat with oil. Brown the meat in batches until golden crust forms on all sides.

Step 5: Combine and Simmer

6. Lower the heat to medium-low. Strain the blended sauce into the pot, scraping the browned bits from the bottom. Cook for 1 minute.
7. Return the browned meat to the pot. Add the water (9 cups) and bay leaves. Stir and bring to a boil. Reduce heat to low, cover, and simmer for 3 hours or until the meat is tender.

Step 6: Shred the Meat

8. Transfer the meat to a large bowl and shred with a fork, discarding any fat. Return half of the shredded meat to the pot and reserve the other half for quesatacos!