In a large bowl, combine olive oil, lemon juice, minced garlic, oregano, paprika, salt, and black pepper. Whisk until fully combined.
Add the chicken breast to the marinade and toss thoroughly to coat every piece evenly. Cover and refrigerate for at least 30 minutes, though 2–8 hours is recommended for maximum flavor.
Remove the chicken from the refrigerator and allow it to sit at room temperature for about 15 minutes before cooking.
Heat a large skillet over medium-high heat. Add the marinated chicken and cook for approximately 6–8 minutes per side, or until the internal temperature reaches 165°F (74°C).
Transfer the cooked chicken to a cutting board and allow it to rest for 5–10 minutes to retain juices.
While the chicken rests, prepare the yogurt sauce by whisking together Greek yogurt, lemon juice, dill, garlic powder, salt, and pepper until smooth and creamy.
Wash and dry all vegetables thoroughly. Dice the cucumber, halve the cherry tomatoes, slice the red onion, and chop the romaine lettuce.
Slice the rested chicken into strips or bite-sized pieces.
Divide the cooked brown rice evenly among four meal prep containers.
Top each container with sliced chicken, cucumber, tomatoes, red onion, romaine lettuce, and feta cheese.
Portion the yogurt sauce into separate small containers for freshness.
Seal containers tightly and refrigerate until ready to serve.
When ready to eat, drizzle the Greek yogurt sauce over the bowl and enjoy warm or cold.