In a large sauté pan over medium-high heat, add the oil and warm until shimmering. Sprinkle the pork generously with salt and add the meat to the pan. Sear the pork until a crust forms, about 4 minutes per side. After one side sears, rotate to sear all the sides and the ends. To do the ends, you may need to hold the pork with tongs and keep it in place.
Add the sliced onion and bay leaf to the slow cooker. Transfer the pork to a slow cooker and place it on top of the onions. Add any remaining salt and a few grindings of freshly ground pepper.
Cover and cook on high for 6-7 hours. After 6 hours, shred the pork with two forks or tongs. If the meat falls apart and shreds easily, change temperature setting to warm, and cover the slow cooker until ready to serve. If the meat doesn't fall apart, return it to the slow cooker, cover, and cook an additional 1-2 hours on low.
To crisp the pork, place the shredded meat in a single layer on a sheetpan and broil on high on the top rack of the oven until slightly browned and caramelized on the edges of the meat, about 1 minute.
Serve with corn tortillas, cilantro, avocado, jalapeños, tomatillo salsa, pickled red onions and hot sauce.