Marinated Chicken Pita Sandwich

INGREDIENTS

• 1/4 cup olive oil
• 1/4 cup lemon juice
• 1/2 teaspoon salt
• 1/2 teaspoon dried oregano
• 1/4 teaspoon garlic powder
• 1/8 teaspoon pepper
• 1 boneless, skinless chicken breast, cubed
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• 1 pocket bread round, cut in half
• 1 small onion, sliced
• 1 tomato, sliced
• 1/2 cup plain yogurt