What is a sign that pre-cooked fries are done?

The sign that pre-cooked fries are done is indicated by their hard outside texture. When fries are fully cooked, the heat causes the exterior to become crisp, which is essential for achieving that signature fry quality that customers expect. This hardening of the outside creates a contrast with the softer interior, resulting in a desirable texture.

In cooking, particularly with frying, texture plays a crucial role in the final product. The hard outside not only contributes to the overall experience but also helps to seal in moisture, keeping the inside fluffy. This principle is widely recognized in culinary practices.

When considering the other aspects mentioned, while fries may float during cooking due to the heat and oil, it isn't a definitive indicator that they are entirely cooked through. Color changes can also happen for various reasons, but a consistent hard texture reliably signals that the fries are finished and ready to serve.