Cut the Pork into four large pieces, and sprinkle generously with kosher salt and cracked black pepper. Heat a dutch oven or a large skillet over medium high heat, and sear the meat in the canola oil, looking to get a little crust on each side of each piece of pork.
Combine the vinegar, garlic, rosemary, honey, fennel, red pepper flakes, 1 Tbsp. salt, and 1 cup water in the insert of slow cooker. Place the pork on top of the liquid, turning with tongs to coat and mix ingredients. Cook on high until pork is very tender and shreds easily, about 4 hours.
Transfer pork to a medium bowl and let rest until cool enough to handle. Pour cooking liquid through a fine-mesh sieve into a medium saucepan; discard solids. Let liquid settle so fat rises to the top, then pour off and discard all but a thin layer of fat. Bring liquid to a simmer over medium heat and cook, stirring occasionally, until reduced by about a third, 12–18 minutes.
Meanwhile, shred pork with your fingers or 2 forks, discarding any large bits of fat. Season with salt.
Set aside 1 cup cooking juices for serving, then add shredded pork to saucepan with remaining juices and toss to coat and rewarm pork.