In a small bowl, mix together the yogurt, lemon juice, and a pinch of salt. Chill in the refrigerator until ready to serve.
To make the onion salad: In another bowl, toss the onion slices with the olive oil, parsley, and salt. Set aside until ready to serve.
To make the meatballs:
In a large mixing bowl, combine the lamb, 1 tablespoon cool water, red onion, parsley, mint, garlic, salt, cumin, allspice, Aleppo pepper, and pepper.
Mix together with your hands until well combined and slightly sticky. Shape the lamb mixture into 12 golf ball-sized meatballs.
Heat 2 tablespoons olive oil in a large skillet over medium-high heat. Working in batches, if necessary, add the meatballs to the hot oil, and cook until browned on all sides and cooked through, about 12 minutes. Set aside and keep warm.
To serve:
Spoon the yogurt onto the warm pitas, and top with the meatballs. Drizzle the meatballs with pomegranate molasses, and spoon the onion salad over the top. Garnish with pomegranate seeds and mint leaves, and serve warm.