Preheat the oven to 425°F (220°C). In a small bowl, combine all dried herbs and paprika. Coat the chicken breasts evenly with olive oil, then rub the seasoning mixture over both sides.
Place the chicken in a baking dish and cook for 20–25 minutes, turning once halfway through, until fully cooked and golden. Allow the chicken to rest for several minutes before slicing.
While the chicken bakes, combine the cucumber, bell pepper, cherry tomatoes, onion, olives, and feta in a large mixing bowl. Drizzle with the Greek dressing and toss until well coated.
Divide the salad among serving bowls. Arrange the sliced chicken on top of each portion and garnish with diced avocado before serving.