Pat the chicken breasts dry with paper towels, then place them in a large mixing bowl. Drizzle with olive oil and season with garlic powder, onion powder, dried oregano, smoked paprika, salt, and black pepper. Toss until the chicken is evenly coated and let it rest for 15–20 minutes so the seasonings can penetrate the meat.

Heat a large skillet or grill pan over medium-high heat. Cook the chicken for 5–7 minutes on the first side without moving it, then flip and cook for another 5–7 minutes, or until the thickest part reaches an internal temperature of 165°F (74°C). Transfer the chicken to a cutting board and let it rest for at least 5 minutes before slicing it into thin strips or bite-sized pieces.

While the chicken is resting, prepare the dressing by whisking together the Greek yogurt, fresh lemon juice, Dijon mustard, minced garlic, chopped dill, chopped parsley, a pinch of salt, and black pepper in a small bowl until smooth and creamy. Taste and adjust the seasoning if needed.

Wash and dry the cucumbers and cherry tomatoes thoroughly. Dice the cucumbers, halve the tomatoes, and finely dice the red onion. Place the vegetables into a large mixing bowl and gently toss them with the prepared yogurt dressing until evenly coated.

Divide the cucumber salad evenly among four meal prep containers. Arrange the sliced chicken beside the salad to help maintain the best texture during storage. If using feta cheese, sprinkle it over the salad, then garnish with the remaining chopped herbs.

Add a lemon wedge to each container if desired for extra freshness. Seal the containers with airtight lids and refrigerate for at least 30 minutes before serving so the flavors can develop.

Enjoy the lunch box cold straight from the refrigerator, or warm only the chicken briefly before serving if you prefer. Store the containers in the refrigerator for up to four days, keeping any extra dressing separate if preparing further in advance.