3 tablespoons extra-virgin olive oil
1 tablespoon lemon juice
1/2 tablespoon dried oregano
1/2 tablespoon kosher salt
1 1/2 cups halved grape or cherry tomatoes
3 Persian cucumbers, cut into 1/2-in. dice, or 1/2 English cucumber, diced
Whisk oil, lemon juice, oregano, and salt together in a large bowl. Add tomatoes and cucumbers and toss well.
Make ahead: Up to 1 day, vinaigrette and vegetables chilled separately.