Use a cast iron skillet (or another pan if you don't have one) and allow it to heat to a high temperature.
Then place fat, onions, and sweet potato in to the pan!
Cook for a minute or two on high heat and then reduce to a medium low heat.
At this point, add in your salt and herbs if you wish!
Then cover and let cook for 10-20 minutes or until the sweet potatoes are cooked to your liking!
Notes
I like making a large batch of this and using it on salads throughout the week. It is also great on mornings when you need a quick breakfast because you can quickly heat it up with some eggs!
Recipe by Holistic Rendezvous at http://holisticrendezvous.com/sweet-potato-hash/