Preparation
Brown the pork roast in a pan with olive oil.
Transfer it to the slow cooker and arrange the onion rings around it.
In a bowl, combine the cider vinegar, soy sauce, honey, brown sugar, garlic, salt, and chili flakes (if using).
Pour this marinade over the pork and onions.
Add the pineapple chunks around the roast.
Cook on low for 6 to 8 hours or on high for 4 to 5 hours, until the pork is tender.
(Optional) Thicken the sauce with a little cornstarch diluted in water if you prefer a creamier consistency.
Serve hot with rice or sautéed vegetables. 
