We recently had this in a restaurant in Zurich. It is supposedly a typical Swiss dish. You can not go wrong with the combination of potato and melted Raclett cheese. We think this is a good dish for Izakaya. It is so simple and there is no real recipe (I just recreated what we had). I used a Russet potato but the dish we had in the restaurant appears to be made using a different kind of potato. (When asked the waitress couldn't identify the type of potato). The dish may work better with something like Yukon Gold. I microwaved the potato in a covered dish for 6-7 minutes or until cooked through (depends on the size of the potato and the wattage of the microwave). I grabbed it using a towel and removed the skin while it is hot (I am sure you could leave the skin if you like). I scooped out the top of the potato to make a groove in the depth of 1/3 of the thickness of the potato and stuffed it with chopped Raclett cheese and placed a few slices to cover the top of the potato. I then put it in a 450F oven for a few minutes. You could also place it under a broiler until the cheese melts. The original we had at the restaurant did not have any garnish but I added chopped chive mostly for color. This is an especially satisfying dish particularly with a little salt on the side to enhance the flavor of those parts of the potato not covered with cheese.
Similar potato dish we also like is "potato and butter" or "jaga-bata" ジャガバタ. You start with a boiled or microwaved whole potato (you could do this step ahead of time). Cut into quoters along the long axis and put them on the grill to make char marks on the cut surfaces and to warm it thoroughly. Then cut in a crosswise fashion in half inch thick slices. Put buttons of butter on it and let it melt. Eat with some salt or with soy sauce. When we go to a near-by Robatakaki/sushi bar called Tako Grill (this is not "taco" and "tako"means "octopus" in Japanese), this is the one we always order.