Cool the Fries. Remove the fries from the oil and place them on a wire rack or paper towels to cool. Let them rest for at least 15 minutes. Cooling helps them firm up for the second fry. Second Fry (Crisping) Increase the oil temperature to 375°F (190°C). Fry the potatoes again in small batches for 2-3 minutes or until they turn golden brown ... More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.