Preheat oven to 550 degrees F, or highest setting.
In a large mixing bowl, toss potato wedges with oil and melted butter. Spread potatoes in a single layer on a cookie sheet. Roast potatoes 20 minutes, turning once, until deeply golden all over.
Season with salt and sprinkle with malt vinegar. Pile fries into a basket or shallow dish, lined with brown paper.
Recipe courtesy of Rachael Ray