Using a large pot, bring 3 litres of water to a rolling boil. Add in the apple cider vinegar (or white vinegar). Place sliced potatoes in the boiling water, then boil for 8 - 10 minutes until just fork tender. Strain, then spread on a parchment lined baking sheet and let cool slightly.
Preheat oven to 375ºF. Drizzle the boiled fries with avocado oil (3-4 tablespoon) and ½ teaspoon sea salt. Toss, then arrange fries to lay flat on the pan. If overcrowded, spread out on two baking sheets.
Bake for 20 minutes, remove from oven and flip fries. Put back in oven, and bake 20 more minutes or until golden and crispy on all sides.
Remove from the oven, and place on a parchment lined serving tray or plate. Sprinkle with chopped parsley, and flaked sea salt. Serve with ketchup, and enjoy!