Preheat the grill to medium-high heat. Season the chicken breasts with salt, pepper, and a drizzle of olive oil. Grill for about 6-7 minutes on each side or until fully cooked.

In a large mixing bowl, combine the chopped romaine lettuce, cherry tomatoes, cucumber, red onion, and feta cheese.

In a small bowl, whisk together olive oil, red wine vinegar, dried oregano, salt, and pepper.

Slice the grilled chicken and add it to the salad. Drizzle the dressing over the top and toss gently to combine.