Preheat the oven to 200 degrees Celsius.
Cut parallel slits into each potato, stopping just before you cut through so that the slices stay connected at the bottom of the potato. I like to cut off the bottom part of the potato (1-2mm) so that it stands steady. I also usually use a spoon or put the potato in the handle of a plastic cutting board to make it easier not to cut all the way through the potato.
Place the potatoes on a baking sheet, brush with olive oil and sprinkle with sea salt. Bake in the oven for 35-50 minutes, depending on how large your potatoes are. If needed brush the potatoes once more after half the baking time. The potatoes are ready when they are soft all the way through and the edges are golden brown and crispy.
When the potatoes are just about ready preheat a nonstick pan with some olive oil or butter.
Add the chanterelles, season with salt and white pepper. Let them fry until golden brown on medium high heat.
Preheat another nonstick pan and sauté the green kale for 1-2 minutes.
Assembly the Hasselback potatoes by adding fried chanterelles, sautéed green kale, lingonberries and finally grating gruyere over them.