Wash and dice cucumbers into half-inch cubes. Halve cherry tomatoes, finely dice red onion, halve olives, and chop parsley, dill, and mint.
Drain both cans of chickpeas in a colander, rinse under cold water for 30 seconds, then pat dry thoroughly with paper towels.
In a small bowl or mason jar, whisk together olive oil, lemon juice, red wine vinegar, minced garlic, oregano, salt, and pepper until emulsified.
In a large bowl, combine diced cucumbers, chickpeas, cherry tomatoes, red onion, olives, and fresh herbs. Toss gently to distribute evenly.
Crumble the feta cheese over the top of the salad in large, uneven pieces.
Pour the dressing over the salad and toss gently until everything is coated. Taste and adjust seasoning as needed.
Let the salad rest in the refrigerator for at least 20 minutes before serving to allow flavors to meld. Serve cold or at room temperature.