If you've never had julienne potato french fries, you haven't lived! All you need is
- julienne-capable mandolin or spiralizer with a julienne option,
- high-smoke cooking oil
- deep fryer or frying pan with high sidewalls
- salt, pepper & seasonings to taste
Now set your slicing device to its julienne setting and turn the potatoes to a pile of "dress shoe strings," or about the thickness of angel hair pasta.
Some types of potatoes need to be washed after slicing to get rid of any excess of starch. The Costa Rican types definitely need this starch-washing.
Dry off the julienned potatoes. We shake them in a sieve and finish on toweling. A salad spinner might be nice. Just get 'em dry.
Heat your oil to 350 F (177C), then deep fry your potatoes. Bring them to a light golden brown, then dump them onto a draining grid or onto several layers of paper towel. Let 'em rest until they're cool enough to touch with your bare fingers, plus or minus -- the exact degree of cooling isn't important.
In a commercial fryer, you can do a big batch all at once. If not, do a fist-full at a time so that the oil temperature doesn't drop much. Be sure to reheat the oil to 350 again before doing subsequent batches.
Now for the crunch ...
Bring your oil up to 380-85 F (193-96 C), then, while hovering over your fryer, plunge a fully submersible batch of the previously fried potatoes into the very hot oil, gently agitating and watching constantly. (They can go from crunchy to burnt in seconds.)
As soon as some of the thinnest ends are dark brown, pull them out.
Again drain them and shake on salt & pepper to taste. We add a light sprinkle of cajun Tony's or the Central American chili pepper blend called Tajín Clásico con Limón. ¡Yum!
We think these are best served hot, right away, but the local kids don't seem to care -- I think they'd eat them frozen.