Peel the potatoes and grate them into a bowl. Also grate your zucchini. Transfer the vegetable mixture onto a kitchen towel, fold it to form a ball and squeeze to remove as much moisture as possible.
Heat a non-stick frying pan over medium heat, add the vegetable oil (or clarified butter). Fill the pan with the potato and zucchini mixture and gently push down. Fry the rösti for 10 minutes on each side or until golden brown, but still tender inside.
Remove from the pan, season with sea salt and drain on kitchen paper. Serve with a generous dollop of sour cream or serve with a bowl of fresh, seasonal salad. Or you can serve it with poached egg, fried egg and bleached swiss chard / spinach. Enjoy.