Preheat oven to 425°F with a rack in lower third position.
Stir 6 tablespoons oil, 2 teaspoons coriander, 2 teaspoons oregano, 1½ teaspoons paprika and ½ teaspoon cracked pepper together in a small bowl.
Toss dried chickpeas, cubed halloumi and onion wedges with 1½ tablespoons of the oil mixture on a large rimmed baking sheet until evenly coated; spread in an even layer.
Roast until the cheese is browned and the chickpeas are starting to crisp, about 12 minutes. Stir and spread into an even layer.
Combine zucchini pieces, 2 cups tomatoes, chopped bell pepper, and 1½ tablespoons oil mixture in a medium bowl; toss to coat.
Spoon evenly over the chickpea mixture on the baking sheet. Roast until the vegetables are tender, about 10 minutes. Sprinkle with ¼ teaspoon salt.
Meanwhile, stir ¾ cup yogurt, 1 tablespoon mint, the grated garlic, 1½ tablespoons oil mixture and the remaining ⅛ teaspoon salt together in a small bowl.
Spread the yogurt mixture evenly over 4 plates, then top with the chickpea mixture. Drizzle with the remaining 1½ tablespoons oil mixture. Garnish with additional mint, if desired.
