Layer sweet potatoes, apples and onion in 3 ½ - to 4-quart slow cooker. Place pork on top.
Pour apple cider over roast; sprinkle with remaining ingredients. Cover and cook on Low 8 to 10 hours (High: 4 to 5 hours).
If you like a very drinkable red wine that can be enjoyed throughout the meal, uncork a bottle of Pinot Noir. Its light, jammy flavor enhances pork and makes each bite perfect.