Moroccan Tacos

Ingredients

• 1 (8-ounce) carton plain low-fat yogurt, divided
• 1 teaspoon ground coriander seeds
• 1 teaspoon ground cumin
• 1/2 teaspoon ground cardamom
• 1/4 teaspoon salt
• 1/4 teaspoon ground red pepper
• 1 pound skinless, boneless chicken breasts, cut into 1-inch pieces
• Cooking spray
• 1/2 cup chopped seeded cucumber
• 1/4 cup chopped fresh cilantro
• 3 tablespoons finely chopped onion
• 1/4 teaspoon sugar
• 3 cups mixed salad greens
• 4 (6-inch) whole wheat pitas, cut in half