Coat a 4-to 6-quart slow cooker with nonstick cooking spray. Cut the pork into 1 ½-inch pieces.
Coat the bottom of a large skillet with oil and place over MEDIUM-HIGH heat. When hot, add half the pork. Season with the ¼ teaspoon salt and ¼ teaspoon pepper and sauté 3 to 4 minutes or until browned (do not cook the pork through at this point). Transfer the browned pork to the slow cooker and repeat with the remaining pork, salt, and pepper.
Combine the sauce ingredients in a small bowl. Pour the sauce and the chicken broth over the pork and stir well to combine.
Cover and cook on LOW for 4 to 5 hours until the pork is fork tender.
About 45 minutes before the end of the cooking time, stir the bell peppers into the pork and sauce in the slow cooker and sprinkle the green onions over the top. Cover and continue to cook on LOW for the remaining 45 minutes, or until the pork is very tender and the vegetables are cooked to your liking.
Combine the water and cornstarch and pour the mixture into the slow cooker and stir to combine. Continue to cook, uncovered, for an additional 5 to 10 minutes to thicken the sauce.
Serve over rice with additional green onions for garnish.
