Steps
1. In a salad bowl, combine mixed greens, sliced red onion, chopped tomato, and olives.
2. Add the drained tuna on top of the salad.
3. Sprinkle the crumbled feta cheese evenly over the salad.
4. In a small bowl, whisk together olive oil, lemon juice, salt, and pepper.
5. Drizzle the dressing over the salad.
6. Toss gently to combine all ingredients before serving.