Season the pork with salt.
Heat the oil in a large skillet over high heat.
Sear the pork in batches until deeply browned on all sides, then transfer it to the slow cooker.
Pour the broth into the hot skillet and scrape up the browned bits.
Add that liquid to the slow cooker with the vinegar, soy sauce, garlic, five-spice, and guajillo chilies.
Cover and cook on low for 8 to 10 hours, or on high for 5 to 6 hours, until the pork pulls apart easily.
Transfer the pork to a bowl and shred it with two forks.
Reduce the cooking liquid in a saucepan if needed, then toss it back with the shredded pork.
Serve with warm tortillas, radishes, cilantro, and lime.