Heat a dry skillet over medium heat. Toast the ancho, guajillo, and chile de árbol for 1–2 minutes per side, until fragrant and pliable.

Transfer to a bowl and cover with hot water. Soak for 20 minutes until softened.

In the same skillet, heat the oil to medium heat and sauté the chopped onion and tomatoes for 5 minutes until softened. Add the garlic and cook another minute.

Drain the soaked chiles and add to a blender along with sautéed veggies, vinegar, oregano, cumin, cinnamon, thyme or marjoram, pepper, clove (if using), and 1 cup beef broth.

Blend until smooth. Strain if you prefer a silky texture.

Add beef chunks to a large bowl and pour the birria sauce over them. Toss to coat. Cover and marinate in the fridge for at least 2 hours or overnight.

Transfer everything (marinated beef and sauce) into your slow cooker. Add remaining 3 cups beef broth and bay leaves.

Cover and cook on LOW for 8-10 hours, or on HIGH for 5-6 hours, until beef is tender and easily shredded.

Remove the bay leaves. Shred the beef with forks.

Serve in bowls with the rich broth from the crockpot (consomé), or use for tacos or quesabirria.