Prepare the potatoes: Cut the potatoes lengthwise 1/2 inch thick to create 3 or 4 slabs per potato. Pat dry with paper towels. Fill a large skillet with 1/2 inch oil and heat over medium-high heat until the temperature reaches about 350°F to 360°F or until you see small waves in the oil and a potato sizzles gently when dropped into the oil. Working in batches, add the potatoes in one layer and cook until lightly golden, 2 to 3 minutes, then turn over and cook until golden on the second sides, about 2 minutes longer. Cut one to test for doneness: it should be fully cooked and soft inside. Drain on paper towels and season generously with salt.