Season the pork loin with salt, pepper, and garlic powder. Heat olive oil in a skillet over medium-high heat and sear the pork for 2 minutes per side. Transfer to the slow cooker.
Whisk together the undrained pineapple, soy sauce, brown sugar, rice vinegar, ginger, and minced garlic in a bowl. Pour over the meat.
Cook on the low setting for 4 to 5 hours until the internal temperature reaches 145 degrees Fahrenheit.
Remove the pork to a cutting board and cover with foil. Turn the slow cooker to high.
Mix the cornstarch and cold water to make a slurry. Stir it into the slow cooker juices and let simmer uncovered for 10 minutes to thicken into a glaze. Slice the pork and serve with the warm glaze.
