In a large bowl, combine olive oil, lemon juice, minced garlic, cumin, paprika, salt, and pepper to create a marinade. Add the chicken breasts and marinate for at least 30 minutes.

Heat the grill or sauté pan over medium heat. Cook the chicken for about 6-7 minutes on each side until it reaches 165°F.

While the chicken rests, prepare fresh toppings by chopping tomatoes, cucumbers, and red onion. For the tzatziki, mix Greek yogurt, grated cucumber, minced garlic, and lemon juice.

To assemble, place a warm pita at the bottom of each bowl, top with sliced chicken, chopped vegetables, and tzatziki sauce.