In a medium bowl, whisk together olive oil, minced garlic, dried oregano, ground cumin, and a pinch of salt and pepper. Coat the chicken with the marinade. Cover and refrigerate for at least 30 minutes.

Preheat grill or skillet over medium-high heat. Cook marinated chicken for 6-7 minutes on each side until golden and internal temperature reaches 165°F. Let rest for 5 minutes and slice.

In a small bowl, combine Greek yogurt with the juice of a lemon. Whisk until smooth. Set aside.

In a mixing bowl, combine diced tomatoes, diced cucumber, chopped red onion, sliced Kalamata olives, and crumbled feta cheese. Toss to mix.

Heat corn tortillas in a dry skillet for 30 seconds on each side until warm. Keep covered with a towel.

Layer sliced grilled chicken, the salad mixture, and yogurt sauce on each tortilla. Garnish with parsley. Serve immediately.