Step 1: Season beef with salt and pepper. Sear in a skillet with oil until browned on all sides.
Step 2: Blend garlic, chipotle peppers, cumin, oregano, smoked paprika, cloves, broth, vinegar, and lime juice into a smooth sauce.
Step 3: Place beef in slow cooker and pour sauce over it. Cover and cook on low for 6–8 hours.
Step 4: Remove beef and shred with two forks. Return shredded beef to slow cooker and mix with sauce.
Step 5: Warm tortillas. Assemble tacos with beef and garnish with cilantro and optional toppings.
Step 6: Serve immediately.