Cut potatoes into long, thin French fry sized slices. We like to leave the skin on our white potatoes but you can peel them if you would prefer. Coat the potato slices in olive oil. Arrange the white potato slices in a baking pan and bake at 350 degrees for about 10 minutes. Add the sweet potato slices and continue baking at 350 degrees for about 45 minutes more. Add salt and pepper to taste and serve.