Greek Chicken Gyros with Tzatziki and Mediterranean Salad

1. In a bowl, combine the chicken thighs with 1 tbsp olive oil, 1/4 cup Greek yogurt, 2 tbsp lemon juice, 1 tbsp dijon mustard, 1 tsp each of salt, pepper, oregano, parsley, paprika, red pepper flakes, garlic powder, and onion powder. Marinate in the fridge for 1 hour (or longer if you have the time).
2. For the tzatziki, mix together 1/2 cup Greek yogurt, 1 minced garlic clove, 1 grated and drained cucumber, 1 tbsp olive oil, lemon juice to taste, and salt to taste in a bowl and allow it to sit in the fridge to let the flavors meld.
3. For the salad, combine 2 diced Roma tomatoes, 1 diced cucumber, 1/2 sliced thin red onion with 1/2 tsp olive oil, lemon juice to taste, and salt/pepper to taste.
4. Grill the chicken and slice it.
5. Grill the pita on each side until golden and brush with garlic butter.