Chicken Souvlaki with Tzatziki Sauce

INGREDIENTS

• 3 tablespoons fresh lemon juice
• 1 1/2 teaspoons chopped fresh or 1/2 teaspoon dried oregano
• 2 teaspoons olive oil
• 1/2 teaspoon salt
• 4 garlic cloves, minced
• 1/2 pound skinless, boneless chicken breast, cut into 1-inch pieces
• 1 medium zucchini, quartered lengthwise and cut into (1/2-inch-thick) slices
• Cooking spray
• 1/2 cup cucumber, peeled, seeded, and shredded
• 1/2 cup plain low-fat yogurt
• 1 tablespoon lemon juice
• 1/4 teaspoon salt
• 1 garlic clove, minced