Boil the unpeeled potatoes for 7 minutes in salted water. Drain and allow to cool. Peel when cooled and grate coarsely. Sprinkle the garlic, salt and pepper and some olive oil. Heat a frying pan with olive oil inside. Take 250g of the potatoes and make a ball out of it with your hands. Place the ball in the pan and press on it to make a flat disk. Bake for a couple of minutes and gently shake the pan back and forth so that the potatoes do not stick to the bottom of the pan. Flip the potato disk and bake the other side until golden brown and crispy. Slide the rösti off the pan and keep warm. Do the same with the rest of the potatoes. Serve warm.