In a medium bowl, whisk together olive oil, lemon juice, minced garlic, oregano, paprika, salt, and pepper. Coat chicken chunks evenly with the marinade and let rest in the refrigerator for 15 to 45 minutes.

Meanwhile, dice the cucumber, tomatoes, bell pepper, and red onion. In a large mixing bowl, combine the diced veggies with chopped parsley and crumbled feta. Season the salsa with lemon juice, salt, and pepper; let sit to meld flavors.

Heat a skillet or grill pan over medium-high heat. Add marinated chicken in a single layer and cook for 3 to 5 minutes on each side until golden brown and cooked through.

While the chicken rests, warm the pitas either by toasting over an open flame or wrapping in foil and warming in the oven at 350°F for 5 minutes.

To assemble the tacos, open each pita pocket and fill with grilled chicken followed by fresh salsa and a drizzle of tzatziki sauce.