Use a spiralizer to cut out the fries (I use a thin spiral setting). Toss them with the oil and a couple of shakes of salt, then spread onto 2 parchment-lined baking sheets. (Make sure you use parchment, since foil or Silpats don't allow the potatoes to wick off enough moisture).
Roast the potatoes one baking sheet at a time at 450F for 20 minutes on the bottom rack, flipping the potatoes halfway through with a big spatula (think the kind you'd use to flip pancakes). Don't worry if the edges seem really dark and there's pale spots; these fries taste best when you have crispy edges and soft, potato-y middles.
Toss the hot curly fries immediately with the sesame seeds, sumac and thyme. Serve hot with the garlic lemon yogurt sauce and ketchup.