Peel potatoes and cut into strips lengthwise (about 3/8-inch thick).
Drop strips into ice water and let stand 1 hour, adding more ice cubes as needed.
Drain and dry well with paper towelling.
Heat fat to 375 degrees.
Fry potatoes a handful at a time, cooking only until very lightly browned.
Separate and turn potatoes with a long-handled fork.
Drain well on paper towelling.
Fry potatoes a second time just before serving time.
Fry until golden this time, about 5 minutes.
Sprinkle with salt and serve immediately.