Place the butter and olive oil in a large skillet over medium high heat.
Once the butter has melted add in the potatoes and onions in a single layer. Season with salt and pepper.
Cover the skillet with a lid and cook for 5-6 minutes.
Flip the potatoes over and cook for another 5-6 minutes or until the potatoes are tender and have a nice crust on them.
Remove from the pan and serve immediately.