Prepare all vegetables: slice cucumbers into half-moons, halve tomatoes, thinly slice red onion, and chop fresh herbs.
If desired, soak sliced red onion in cold water for 10 minutes to mellow its flavor, then drain and pat dry.
Crumble feta cheese into bite-sized pieces using your hands or a fork.
In a small bowl or jar, whisk together olive oil, lemon juice, dried oregano, salt, and pepper until well combined.
In a large mixing bowl, combine cucumbers, tomatoes, red onion, feta, dill, and mint.
Pour dressing over salad ingredients and gently toss until everything is evenly coated.
Let salad rest at room temperature for 5-10 minutes to allow flavors to meld.
Taste and adjust seasoning with additional salt or pepper if needed.
Transfer to serving bowl or individual plates and enjoy immediately.