In a large, lidded skillet, place oil and butter on medium low and add onion and a pinch of salt.
Cook while stirring occasionally until the onions are lightly browned, about 15 to 20 minutes.
Increase the heat to high/medium high and add the sweet potatoes, stir to keep from burning, while darkening the caramelized onions and slightly browning the potatoes, 5 minutes.
Reduce the heat to a simmer and add the garlic, brown sugar, and water, cover and simmer 7 minutes.
Add the apples to the skillet, stir in and cover for 3 more minutes.
Uncover the skillet, check the apple for softness and cook longer if desired, and also adjust the seasoning by adding salt and pepper to taste.
Garnish with chopped parsley and serve hot.