IKOO has the best Japanese noodle soups in Zurich. Very authentic. You can also find some rice dishes with meat or fish on the menu. The restaurant is rather small with very friendly service. At noon you should be on site on time (reservations only possible in the evening) or stop by around 1 pm. The same preparation method can also be found in the sister company MIKI Ramen at Lochergut.
My Tip: Definitely the Tantanmen - a poem