Wash the tomatoes and cucumbers under running water.
Peel the cucumbers if desired, then slice them into rounds or half-moons.
Then, cut the tomatoes into bite-sized chunks.
Thinly slice the onion.
In a mixing bowl, combine the sliced cucumbers, tomatoes, and onions.
In a small bowl, whisk together the olive oil, vinegar, salt, and pepper to make the dressing.
Pour the dressing over the cucumber, tomato, and onion mixture.
Gently toss everything together until well coated in the dressing.
Taste and adjust seasoning if needed.
You can garnish with chopped green onions before serving. (Optional)
Serve chilled or at room temperature and enjoy your refreshing salad!