Heat the butter in a large skillet over medium-high heat and saute the leek until softened, 5-7 minutes. Add the wine, bring to a rapid boil, and boil for 2 minutes until the alcohol has evaporated. Season with salt and pepper. Transfer to a bowl and set aside.

Add the butter and olive oil to the same skillet and heat over medium-high. Once hot, add the potatoes and fry until browned on all sides. This will take several minutes. Don't turn the potatoes over too frequently to prevent the skins from coming loose. Return the leek to the potatoes and stir to combine and heat through.

Transfer the potatoes to a warmed serving platter and serve immediately garnished with fresh chopped parsley.