Prepare the roast: Pat the meat dry and season generously with salt and pepper. If you are searing, heat olive oil in a heavy skillet over medium-high heat and brown the roast on all sides, 3–4 minutes per side. This step is optional but adds depth to the final flavor.

Sauté the aromatics: In the slow cooker, scatter the sliced onion and minced garlic. If you seared the meat, transfer it to the cooker now on top of the onions.

Make the flavorful sauce: In a small bowl, whisk together minced chipotle peppers, adobo sauce, tomato paste, brown sugar, cumin, chili powder, smoked paprika, oregano, and beef broth. This will become the glossy, smoky bath for the meat.

Slow-cook to tenderness: Pour the sauce over the roast. Cover and cook on LOW for 8–9 hours or HIGH for 4–5 hours, until the beef shreds easily with two forks and the sauce is deeply colored and fragrant.

Shred and finish: Remove the roast to a cutting board and shred. Return the meat to the slow cooker and stir to coat in the sauce. Let it simmer 10–15 minutes so the flavors meld and the beef glazes nicely.

Brighten and taste: Stir in 1–2 tablespoons of lime juice and taste for seasoning. Adjust salt if needed. The beef should be juicy, smoky, and slightly sweet with a tangy finish.

Warm tortillas and set the stage: Heat tortillas in a dry skillet or wrap in a damp towel and microwave for a quick warm-up. Gather toppings and lime wedges for serving.

Assemble and serve: Spoon the beef into warm tortillas, top with cilantro, onion, avocado, cotija, and a squeeze of lime. A quick salsa verde or pico de gallo pairs beautifully if you have it on hand.