What is Truffle Oil ? Truffle oil is a modern culinary ingredient, used to impart the flavor and aroma of truffles to a dish. Truffle oil is commonly used to make "truffle fries," which feature french fries cooked in truffle oil, parmesan cheese, pepper, and sometimes other ingredients Truffle oil, available in all seasons and steady in price, is popular with chefs (and diners) because it is significantly less expensive than actual truffles, while possessing some of the same flavors and aroma