Peel and thinly slice the potatoes with a mandoline or in a food processor, using the thin slicing blade.
In a deep fryer, wok, or large heavy pot, pour oil to a depth of about 4 inches, and heat over medium-high heat until the surface of the oil shimmers, and a few drops of water sizzle when flicked into the oil.
Fry the sliced potatoes in batches until crisp and golden brown.
Drain on paper towels.
Sprinkle with salt and chili powder.
Squeeze on lime juice.
Serve warm on sturdy paper plates or heavy brown paper or in small brown paper bags.