In a small bowl, combine yogurt, mayonnaise, vinegar, and a pinch of salt and pepper. Whisk until creamy and smooth.

Thinly slice the onion and soak in cold water for about 10 minutes, then drain and pat dry.

Bring salted water to a boil and cook pasta according to package instructions until al dente, about 8-10 minutes; drain and rinse under cold water.

Wash cucumbers, cut in half lengthwise, scoop out seeds, and slice thinly.

In a large bowl, combine cooled pasta, drained onion, and sliced cucumber. If desired, add cherry tomatoes or bell peppers.

Pour the dressing over the salad and toss gently to coat. Let the salad rest in the refrigerator for at least 40 minutes before serving.