Add the sliced apples and onions on the bottom of the slow cooker.
Place the pork chops on top of the apples and onions.
In a jug, combine the 1½ cups water, tomato sauce, apple cider vinegar, onion powder, garlic powder, Worcestershire sauce, salt, dried sage, sugar and chicken stock powder. Stir well.
Pour the sauce mixture over the pork, apples and onions.
Cover and cook on Low for 6–8 hours or High for 4–6 hours, until the pork is tender and beginning to fall apart.
Towards the end of the cooking time, combine the ¾ cup cold water and cornflour until completely smooth.
Stir the cornflour mixture into the slow cooker. Replace the lid and continue cooking until the sauce has thickened.
Taste and adjust the seasoning if needed, then serve hot.