Hoba-zushi is a local dish of the south of Hida region (Gifu Prefecture), and of Tono (the eastern Mino region of Gifu), and of Chuno (the middle Mino region of Gifu), and of Kiso region (Nagano Prefecture). It is also made in Yoshino region of Nara Prefecture.
Although it is common to use hoba (leaves of magnolia), recipes greatly differ among regions.
As Hida region and Tono region and Chuno region join each other, sometimes two recipes are found in a part and it is difficult to draw a clear line; however since in mainly around those regions Hoba-zushi has been made, it can be said that this sushi had spread from Gifu Prefecture.
First cut a salmon (it is called 'masu' [trout] in Hida region) into a size of about 1cm and soak it raw in vinegar for one night or so. The next day start preparing sushi. First boil rice. Meanwhile mince young shoots of Japanese ginger. When rice is cooked, prepare a big bowl and put rice, salmon (with vinegar) and Japanese ginger in it one after another to mix it evenly. After put all the ingredients, cover it with leaves of magnolia ('hoba'). However don't put a weight on it. After a while, vinegar soaks into rice enough to become good to be eaten. At some homes other ingredients such as takenoko (bamboo shoots) are added, so the tastes differ among different homes. However, the number of ingredients is relatively small. Recently sometimes sliced salmons are boiled (or simmered in soy sauce) or cooked in other ways so that the time for soaking it in vinegar becomes shorter to one hour or so.
At the table, have a leaf of magnolia ('hoba') in one hand, take still-steaming vinegar rice ('sushi' or 'sumeshi') from a bowl with a shamoji (a wooden spoon), put it on the leaf and put leaves of sansho (Japanese pepper) over the rice, and form it like normal sushi by hands and eat it. At this moment, flavors of magnolia and sansho float.
In this region at each home Hoba-zushi are made, so in gardens of houses, in fields, and in open spaces, magnolias are often found.
Tono, Chuno, Kiso regions of Nagano Prefecture
Since the fast past, there have been many families engaged in agriculture or forestry, and such people often had lunch at fields or in mountains.
Hoba-zushi is not only good for being carried and preserved because leaves of magnolia and vinegar rice have antibiotic effects but also convenient as a meal served when neighbors gather to work, therefore, it is considered that Hoba-zushi spread among the people. The season Hoba-zushi is made traditionally overlaps with the season of rice planting, and this fact also shows that Hoba-zushi has been related to agriculture and forestry.
In Chuno region, when June comes, white blossoms of magnolias are often found along national roads and mountains, which tell us the coming of early summer and the season of Hoba-zushi.
Prepare vinegared rice beforehand. Put the vinegared rice on a leaf of magnolia, and put various ingredients on the rice, and finally fold the leaf into the shape of a square, and tie it with a string. The ingredients have a wide variety including sliced salmon, kanroni (a dish boiled in a syrup) of freshwater fish, maitake mushroom, bracken, kyarabuki (stalks of butterbur boiled in soy sauce), red pickled ginger, denbu (mashed and seasoned fish, flesh of whitefish and shrimp that has been boiled, shredded, parched, seasoned, and colored red), shimesaba (salted and vinegared mackerel), cucumber, minced pickles, and so on; they are mainly Yama-no-sachi (edible wild plants and freshwater fish) since the regions are surrounded by high mountains. As some homes cool vinegared rice or others set sushi in a wooden bowl to put a weight on it, methods and ingredients range widely depending on each home.
Northern area of Chuno region
The area is also referred to the region of Gujo City.
Prepare vinegared rice in sushi oke (a wooden bowl for sushi rice) beforehand. Put small fish, boiled and seasoned carrot, burdock root, shiitake mushroom, salmon and so on in the rice, and mix them well. After mixing the rice (becomes 'sushi') equally, wrap the sushi with leaves of magnolia, set them in a wooden bowl or other container, and put a weight on it not to press it heavily.