In the bottom of a slow cooker, combine the water, soy sauce, fish sauce, hoisin sauce, brown sugar, chili paste and rice vinegar. Toss in the ginger, garlic, lemongrass, and onion.
Season the pork with salt and pepper and nestle the pork in the slow cooker, coat with sauce. (You can also sear your pork prior to adding it into the slow cooker on the stove if you prefer a caramelized skin).
Cook on low for *7 to 8 hours or on high for 4 to 5 hours, rotating once during the cooking process and coating with more sauce.
Transfer the pork to a cutting board and shred using two forks. Dump the pork back into the slow cooker, squeeze in some lime juice and toss to combine with the remaining sauce.
*If your slow cooker runs hot, check on pork earlier.