There are pros and cons to heating frozen fries in the oven or on the stove. The oven can provide even heating and consistent results, while the stove can be faster but can also lead to uneven cooking. Ultimately, it comes down to personal preference and convenience. However, it is not recommended to reheat frozen fries in the microwave as this can result in uneven heating and a soggy texture. If you do choose to use the microwave, be sure to follow package instructions for optimal results.