Preheat the oven to 400°F. Line a large baking sheet with parchment paper. Cut the potatoes into 1-inch thick wedges and transfer them to the baking sheet. Toss them with the oil, shawarma spice blend, and salt. Space the potatoes out so that each wedge has about an inch of space. Place potatoes in the oven and roast for about 40 minutes, or until tender and golden brown, flipping them at the halfway point.
While potatoes are roasting, make the veg salad. In a medium bowl, combine the cucumber, tomatoes, red onion, roasted red pepper, olives, parsley, chickpeas, shawarma spice, lemon juice, olive oil, and salt. Toss to combine and set aside.
Make the lemony tahini. In a medium bowl, whisk together the tahini, water, lemon zest, lemon juice, garlic, salt, and pepper. Once combined and seasoned to your liking, set aside.
Lastly, make the cheesy sesame sprinkle. In a spice grinder, combine the sesame seeds, nutritional yeast, onion powder and salt. Pulse the grinder a few times until you have a fine meal. Set aside.
Build the loaded shawarma-spiced fries. On a platter, arrange the shawarma-spiced fries in a single layer. Drizzle the fries with the lemony tahini. Spoon the crunchy veg salad on top, ensuring that you strain off the excess liquid at the bottom of the bowl. Finish the loaded shawarma-spiced fries with the cheesy sesame sprinkle and extra chopped parsley if you like.