Preheat oven to 375°F. Brush a baking sheet with the olive oil and place in the hot oven for 10 minutes.
In a large bowl, toss together the potatoes, cornstarch, cumin, paprika, mint, Aleppo pepper, salt, and black pepper until evenly combined. Dump out onto the prepared baking sheet, making sure they're all facing cut-side down. Bake for 12 minutes.
In the meantime, in a large bowl, stir together the ground beef, bread crumbs, onion, parsley, cumin, paprika, Aleppo pepper, mint, salt, pepper, egg and olive oil until well combined. Shape into 1-inch meatballs.
Carefully remove the baking sheet from the oven and add the meatballs among the potatoes, in an even layer. Return to the oven and bake for another 15 minutes.
In a large bowl, whisk together the tahini with the cold water, lemon juice and salt until smooth. Whisk in the yogurt and grated garlic. Mixture should be smooth, somewhat thick but still a bit pourable. If it's too thick, loosen with a tad more water or lemon juice.
Pour tahini yogurt sauce onto serving platter and spread out evenly. Top with the roasted potatoes and köfte. Top with pine nuts and parsley. Serve immediately and enjoy!