Preheat oven to 375°. In a small bowl, mix the first five ingredients. Rub over cauliflower; arrange in a foil-lined 15x10x1-in. baking pan coated with cooking spray, cut sides up. Roast 40-45 minutes or until golden brown and tender.
For sauce, in a small bowl, mix yogurt, lemon juice, tahini, salt, paprika and pepper; serve over cauliflower. Sprinkle with parsley.