For an extra layer of flavor, consider searing the pork loin in a hot pan before adding it to the slow cooker. This will create a beautiful crust and enhance the overall taste. Adjust the amount of chipotle pepper to your preference. If you prefer a milder flavor, use only half a pepper or remove the seeds. Serve the Tacos al Pastor on warmed corn tortillas with your favorite toppings, such as chopped fresh cilantro, crumbled queso fresco, diced red onion, a squeeze of lime juice, or a dollop of sour cream.