In a large bowl, whisk together the yogurt, lemon juice and oil. Set aside.
Peel the cucumbers and cut them in half lengthwise. Cut each half crosswise into 1-inch segments. Spread the pieces out on a cutting board, flat-side down, and use a heavy pot or skillet to lightly smash the cucumber pieces.
Transfer the smashed cucumbers to the bowl with the yogurt. Add the red onion, dill and parsley, along with a generous pinch of flaky sea salt and a few big grinds of pepper. Toss gently to combine. Taste and season with additional salt and pepper as needed.