Clean and peel potatoes. Using a French fry cutter, cut the potatoes into fries or, alternatively, cut the potatoes into desired size. Place the fries in a large bowl filled with cold water and let sit for 1 hour and up to 24 hours for extra-crispy fries.
In a saucepan, heat the vegetable oil on medium heat and saute the shallots and garlic until translucent, about 3 minutes. Add the veal stock, ketchup, cider vinegar, peppercorns, and Worcestershire sauce and bring to a boil.
Meanwhile, in a separate saucepan on medium-high heat, melt the butter. Add the flour and stir for 2 to 3 minutes, making a roux. Allow to brown slightly. Whip the roux mixture into the stock and let simmer for about 20 minutes, until reduced by half and thickened. Season the sauce with salt and pepper. Keep warm.
In a deep-fryer set to 250 degrees F, blanch the fries in oil for about 2 minutes. Remove the fries and let them rest for about 5 minutes. Then, fry them again for about 2 minutes or until golden brown. Place on a paper towel-lined baking tray to absorb the excess oil. Salt and pepper the fries while hot. Remove the sauce from the stovetop and strain. Plate the fries in a shallow bowl, pour sauce on top and garnish with cheese curds.