In a large bowl, whisk together olive oil, minced garlic, dried oregano, ground cumin, salt, and pepper to create a marinade. Add chicken and coat thoroughly. Cover and marinate for at least 30 minutes.

Preheat your grill or skillet to medium-high heat, about 375°F. Cook the marinated chicken for 6-7 minutes per side until cooked through. Let rest for 5 minutes and slice thinly.

In a small bowl, combine Greek yogurt and lemon juice, whisking until smooth and creamy for the sauce.

In a mixing bowl, combine diced tomatoes, cucumber, red onion, olives, and feta cheese. Toss gently to combine.

Heat a dry skillet over medium heat and warm each tortilla for about 30 seconds on each side.

Assemble tacos by placing sliced chicken on each tortilla, topping with salad mix, drizzling with yogurt sauce, and garnishing with parsley. Serve immediately.