For the patties: Heat the olive oil in a large skillet over medium heat. Add the onion and a pinch of salt and cook until soft, 5 to 7 minutes. Add the garlic, coriander, cumin and cinnamon and cook until fragrant, another minute. Remove from the heat and let cool slightly.
Meanwhile, combine the egg and breadcrumbs in a large bowl. Add the turkey, spread it out, and sprinkle it evenly with 3/4 teaspoon salt, a few turns of black pepper, the crushed red pepper, cilantro and the slightly cooled onion mixture and use your hands to mix to combine. Do not overmix. Form into 4 balls, then flatten the balls into patties (make the patties bigger in diameter than you ultimately want them since they'll shrink while cooking—about 4 inches is good. If you're forming these in advance, place them on a parchment-lined baking sheet, cover with plastic wrap and refrigerate until ready to cook.
Heat a large skillet with a thin layer of olive oil over medium-high heat. Sprinkle both sides of the patties with salt and pepper and cook until browned and the patties have an internal temperature of 160 degrees F, about 5 minutes on each side.
For the tahini yogurt sauce: Stir together the yogurt, tahini, garlic, lemon zest and juice in a bowl until smooth and spreadable. Stir in the mint and season with salt and pepper and hot sauce, if using.
For serving: Toast the buns in the skillet used for the patties, adding a little more olive oil as needed, until they get lightly browned and crisp around the edges. Assemble the burgers with a slathering of tahini yogurt sauce, a little pile of onions, a leaf of romaine and a couple of torn fresh mint leaves. Enjoy!