In a large bowl, whisk together olive oil, lemon juice, minced garlic, oregano, and paprika until well combined. Cut the chicken into even chunks, coat thoroughly in marinade, and let sit for at least 15 minutes.

Chop the cucumbers, tomatoes, bell peppers, and red onion into small pieces. In another bowl, combine with feta cheese, drizzle with lemon juice, season with salt and pepper, and mix gently.

Heat a skillet over medium-high heat. Add the marinated chicken, cook for about 6-10 minutes, flipping once, until it reaches 165°F.

Warm the pitas by placing them over a gas flame for about 30 seconds per side or heating them in a dry skillet until pliable.

Assemble each pita with grilled chicken, vegetable salsa, and tzatziki. Enjoy your tacos!