How to Make It
Preheat broiler to high. Position oven rack 6 inches below heating element.
Line a baking sheet with foil; set a wire rack on top of foil. Coat rack with cooking spray. Combine quinoa, onion, mint, 2 tablespoons yogurt, cumin, 1 teaspoon garlic, and next 5 ingredients (through paprika) in a food processor; pulse until finely chopped. Add beef; pulse until well blended.
Divide mixture into 8 equal portions. Form 1 portion of beef mixture into a 3 1/2-inch-long patty around an 8-inch metal skewer; place on prepared wire rack. Repeat with remaining beef mixture. Place baking sheet in oven; broil 4 minutes. Turn skewers over; broil 3 to 4 minutes or until browned.
Combine remaining 2 tablespoons yogurt, 1 tablespoon water, tahini, juice, honey, and remaining 1/4 teaspoon garlic in a small bowl, stirring with a whisk.
Arrange cucumber and tomato on a platter. Top with kebabs; drizzle with sauce. Serve with lemon wedges.