Using a vegetable peeler, shave the zucchini and squash lengthwise into ribbons. In a medium bowl, toss the squash and zucchini ribbons with the red onion and oregano.
In a small bowl, whisk the olive oil, lemon juice, and zest until well combine. Season to taste with salt and pepper.
Toss the vegetables with the dressing and top with crumbled feta cheese, if you like.
Recipe by Three Many Cooks at https://threemanycooks.com/recipes/salads-and-sides/zucchini-and-summer-squash-ribbons-with-lemon-vinaigrette/