Boil vinegar, 2 quarts of water, and 2 tablespoons of salt. Boil the potatoes in batches for 7 minutes, make sure the water boils again in between batches. Potatoes should be fully tender, but not falling apart.
Drain and spread on paper towel-lined rimmed baking sheet. Allow to dry for five minutes.
Meanwhile, heat oil in 5-quart Dutch oven or large wok over high heat to 400°F. Add 1/3 of fries to oil (oil temperature should drop to around 360°F). Cook for 50 seconds, agitating occasionally with wire mesh spider, then remove to second paper-towel lined rimmed baking sheet. Repeat with remaining potatoes (working in two more batches), allowing oil to return to 400°F after each addition. Allow potatoes to cool to room temperature, about 30 minutes
Continue with step 3, or for best results, freeze potatoes at least over night, or up to 2 months.
Return oil to 400°F over high heat
Fry half of potatoes until crisp and light golden brown, about 5 minutes, adjusting heat to maintain at around 360°F.
Drain in a bowl lined with paper towels and season immediately with kosher salt.
Cooked fries can be kept hot and crisp on a wire rack set on a sheet tray in a 200°F oven while second batch is cooked. Serve immediately.