In a large bowl, combine the chopped lettuce, halved cherry tomatoes, diced cucumber, diced bell pepper, and sliced red onion.

In a separate small bowl, whisk together the olive oil, lemon juice, salt, and pepper.

Pour the dressing over the salad and toss gently to combine all the ingredients.

Add the grated Parmesan cheese on top and give it another light toss.

If desired, sprinkle with chopped fresh herbs before serving.