In a medium bowl, whisk together olive oil, minced garlic, dried oregano, ground cumin, salt, and pepper until blended. Coat the chicken breasts generously with the marinade and allow marinating for 30 minutes at room temperature, or refrigerate for up to 2 hours.

Preheat your grill or a skillet over medium-high heat. Grill the marinated chicken breasts for 6-7 minutes per side, or until browned and fully cooked. Remove from heat and let rest for 5 minutes before slicing.

Combine Greek yogurt and lemon juice in a small bowl. Whisk until smooth and creamy to create the yogurt sauce.

In a separate bowl, mix the diced tomatoes, cucumber, red onion, Kalamata olives, and feta cheese. Toss gently.

Heat tortillas in a dry skillet over medium heat for 20-30 seconds on each side until warm.

To assemble, lay slices of chicken on each tortilla, add the salad mixture, and drizzle with yogurt sauce. Garnish with parsley.

Serve immediately while warm for the best experience.