Ingredients 2 tablespoons unsalted butter 2 tablespoons olive oil 1 1/2 pounds russet potatoes, peeled and 1/2-inch diced 1 1/2 cups chopped yellow onions (2 onions) 2 teaspoons kosher salt 1 teaspoon freshly ground black pepper 2 tablespoons minced fresh flat-leaf parsley 2 tablespoons minced scallions (white and green parts) Directions Melt the butter with…