Yomogi Dumplings! You get them from Tsuyukusa Town at like, B rank, require Adzuki Beans, Soy Sauce, and mugwort, which grows around north town every few days at the four hydrangea spots in Spring. Best of luck! (He also likes most other Tsuyukusa desserts, so I give him like Monaka most days and save the dumplings for special occasions.)