Combine the 1 1/2 teaspoon kosher salt, 1 teaspoon paprika, 1 teaspoon onion powder, and 1 teaspoon ground ginger in a small bowl. Pat the 3-4 pound boneless pork loin dry with paper towels then rub in the spice mixture.
Heat the 1 tablespoon vegetable oil in a large skillet over medium high heat.
Sear the pork in the hot pan until browned on each side, beginning on the fat side down for 4-5 minutes on each.
In the same bowl as the spice mixture, whisk together the 1/2 cup light soy sauce* with the juice from the can of pineapple chunks, you should get about ¾ cups of juice from the can.
Place half the pineapple chunks on the bottom of the slow cooker then place the seared pork loin on top of them with the fat side up.
Top the roast with the remaining pineapple chunks, diced 1/2 large sweet onion, and pour the soy sauce/pineapple juice mixture over the top.
Cover and cook on high for 4-5 hours. The pork should register at 145°F using an instant read thermometer. See notes about making it sliceable and sizes of pork loin.
Remove the roast to a plate and set aside to rest. Strain the liquid from the slow cooker through a sieve into a medium saucepan over medium heat and bring to a simmer. Reserve the pineapple chunks from the slow cooker, but discard other solids.
Whisk the 1 tablespoon cornstarch with 1 1/2 tablespoons cold water to make a slurry then slowly whisk it into the simmering sauce. Continue to stir gently until it thickens and coats the back of a spoon.
Shred the pork using two forks and then spoon the sauce and reserved pineapple chunks over top. Garnish with chopped 2 tablespoons scallions .
If you've tried this recipe, come back and let us know how it was in the comments or star ratings.
Video
Notes
* Make sure you are familiar with your soy sauce and the levels of salt it has. Different brands are saltier than others. If yours is particularly salty or you do not like salty foods, then omit the additional 1 1/2 teaspoon of salt.