Place pork in a 3- to 4-quart slow cooker. Sprinkle taco seasoning over pork. Pour lime juice and 1/2 cup water over pork. Cover and cook on low for 6 to 7 hours.
Transfer pork to a cutting board. Shred pork using two forks. Return shredded meat and the cilantro to cooker and stir to combine with cooking liquid. Serve meat in flour tortillas with desired toppers.