Quarter the chile and remove the seeds and membranes. Finely chop the chile. Handle pieces carefully, preferably while wearing gloves; they are extremely hot.
Transfer quartered and chopped chiles to a gallon-sized ziploc bag. Add onion, bell peppers, cilantro, salt, pepper, thyme and garlic. Stir in vinegar, orange juice, lemon juice, and lime juice. Mix in pork. Seal and refrigerate overnight.
The next day, remove from refrigerator and pour the contents of the bag into your slow cooker. Cook on low for 6-8 hours. If possible, stay closer to 8 to avoid pork drying out.
Using a slotted spoon, remove meat from slow cooker. Transfer meat to a rimmed baking sheet. Drizzle meat with 2 tablespoons oil and salt to taste, and toss gently to coat.
Strain cooking liquid, discarding any solids, over a cooking pot. Bring sauce to a simmer over high heat until reduced by about half, about 25 to 30 minutes.
Meanwhile, heat the broiler. Broil meat, tossing occasionally, until meat is evenly browned, about 5 to 10 minutes. You want it nicely browned in spots but not so brown that it dries out.
To serve, drizzle meat with sauce and cilantro. Serve on a bed of rice or in a corn tortilla topped with pikliz.