California Grilled Chicken Pita and Tzatziki

1. Prepare the tzatziki by combining all ingredients. Mix well and set aside.
2. In a large bowl, combine the chicken, crumbled feta (optional), minced red onion, minced garlic, oregano, salt, and pepper. Mix until well combined. Divide the mixture into equal portions, shaping each into ½-inch thick burgers. 
3. Heat a grill pan over medium-high heat. Spray the grill pan with cooking spray. Add the burgers to the pan, cook 3-4 minutes, flip, and cook an additional 3-4 minutes until the burgers are cooked through completely.   
4. Cut a strip off of each pita to create a pocket. Place one burger into each pita pocket. Top each with cucumber, red onion, avocado, grape tomatoes.
5. Drizzle each with tzatziki. Serve.  

Serving Suggestion: Sprinkle with crumbled feta cheese and serve with Mediterranean Pasta Salad with Artichokes and Avocado.