Wash all vegetables thoroughly.
Slice the cucumber into thin rounds.
Chop the romaine lettuce into bite-sized pieces.
Thinly slice the red onion.
In a large salad bowl, combine cucumber, lettuce, and onion.
Add cubed feta cheese and Kalamata olives to the bowl.
In a small bowl, whisk together olive oil and lemon juice.
Drizzle the dressing over the salad mixture.
Season with salt and pepper to taste.
Gently toss the salad to combine all ingredients.
Garnish with fresh dill before serving.