Best french fries I ever had were when I was a NATO exchange officer in Brussels. There was a small family-run fries-ony place half-a-block from my apartment. They had a zillion special sauces which I never tried. Finally, my curiosity and my language skills got to the point I asked their secret. They pointed to the fry-laden racks above the friers. They pre-cooked the fries ahead-of-time and placed them in the racks. When a customer ordered, they took down the appropriate amount and threw them in the frier for under a minute. They claimed the double-cooking was the secret. It had the added benefit of quick service even for big orders. BTW, Belgians resent the term french fries, claiming they were invented in Brussels.