Homemade French Fries with Five Dipping Sauces

Peel potatoes, then cut lengthwise into 1/3-inch-thick sticks, submerging in a large bowl of ice water. Rinse potatoes in several changes of cold water in bowl (more ice isn't necessary) until water is clear. Drain in a large colander.
Spread potatoes out in a single layer on several layers of kitchen towels to drain, then pat dry.
While potatoes are being rinsed and dried, heat 2 inches oil slowly in a 5- to 6-quart pot over medium-low heat until thermometer registers 300°F.
When oil is ready, increase heat to high and fry potatoes in four batches, stirring occasionally, until just cooked through but still white, about 3 minutes. (Adjust heat to keep oil as close to 300°F as possible and return oil to 300°F between batches.) Transfer fried potatoes with a slotted spoon to a baking sheet lined with dry towels to drain. When all potatoes are fried once, cool potatoes to room temperature, about 30 minutes.
Reheat oil over medium-high heat until thermometer registers 375°F. Fry potatoes again in four batches, stirring, and adjusting heat to keep oil as close to 375°F as possible, until deep golden, 3 to 4 minutes. (Return oil to 375°F between batches.) Transfer with slotted spoon to dry towels to drain briefly, then season with salt and serve immediately, with sauce(s) for dipping.