Final answer:
The process mentioned in the question is blanching, which involves pre-cooking fries until slightly hard with a slight change in color. This technique improves texture and ensures fries cook evenly by partially cooking them before final frying at a higher temperature.
Step-by-step explanation:
When it is recommended to pre-cook the fries until they are slightly hard with a slight change in color, the goal is to achieve a process known as 'blanching'. Blanching fries before frying them fully allows for a better texture and can help the fries to cook more evenly when they are finished cooking. To do so, you would fry the cut potatoes at a lower temperature until they're soft but not browned, which usually results in a slight change in color indicating that they are partially cooked but not fully crispy.
Not only does blanching improve the final texture, but it also improves the overall cooking process by ensuring the inside of the fries are fully cooked before they are crisped up at a higher temperature.