Boil the potatoes and cut into thick slices. At the same time cut the fennel into thin slices and fry with half the oil. It should still be crisp. Remove from the pan and fry the onions with the remaining oil. Pour the maple syrup over the pan and let it caramelize.
Put everything together in a bowl, pour the pan juice over and season. The salad tastes lukewarm best. If it is too dry, add some vegetable stock and olive oil.