Toss the French fries with the dried oregano and olive oil, then cook following pack instructions.

While the fries are cooking, mix the cucumber with the black olives, cherry tomatoes and parsley. Mix the Greek yogurt with half of the crumbled feta in a separate bowl. Tip the fries into a serving dish, top with the salad and yogurt mixture, then scatter over the remaining crumbled feta. Season and serve.