I think they are so yummy in CH due to a different oil. Any speculation as to what this oil might be? Sunflower?
I loved the chips in CH. In the US, most places use soybean ("vegetable") oil.
I consider that the best for chips is Groundnut (Peanut) Oil.
I second that for peanut oil - high smoke point ( the ability to be brought to and sustain high heat without smoking ). As for potatoes, I seek out for these whenever possible or alternatively the Spunta.
Suggested Recipe
Russet burbank ( also known as an idaho potato in many cookbooks ), with its floury texture and low moisture content, makes the perfect chip, but you can also use bintje or spunta.
INGREDIENTS
1kg russet burbank potatoes, peeled
peanut oil, for deep-frying
METHOD
Cut potatoes lengthways into 1cm slices; cut each slice lengthways into 1cm-wide pieces. Stand potato pieces in large bowl of cold water for 30 minutes to avoid discolouration. Drain; pat dry with absorbent paper.
Heat oil in deep-fryer, wok or large saucepan; cook chips, in 3 batches, about 4 minutes each or until just tender but not browned. Drain on absorbent paper; stand 10 minutes.
Reheat oil; cook chips, in 3 batches, separating any that stick together by shaking deep-fryer basket or with a slotted spoon, until crisp and golden brown. Drain on absorbent paper.
TIPS After the first cooking, the chips can stand for several hours before the final deep-frying.
Corn oil or vegetable oil can also be used.
Good luck.