Browse Techniques

Ginnan (銀杏)—ginkgo nuts—are one of Japan's most exclusively seasonal autumn ingredients, harvested from the female ginkgo tree (Ichō, Ginkgo biloba) in October through November. The ginkgo tree is a living fossil, essentially unchanged for 200 million years, and is deeply embedded in Japanese cultural life as a temple and shrine tree—many of Japan's most famous ginkgo specimens are found at Shinto shrines and Buddhist temples where they have stood for centuries. The fruit's external flesh contains urushiol (the same skin-irritant compound found in poison ivy) and must be removed by fermentation or washing before the inner nut is extracted. The inner nut—pale green when young, turning increasingly bitter as it matures—is used in several canonical Japanese preparations: the clearest dashi-simmered ginnan (with just light soy) showcasing the nut's subtle character; skewered ginnan grilled with salt as a yakimono accompaniment; incorporated into chawanmushi; and cooked into autumn takikomi gohan with other seasonal elements. The flavour is described as 'resinous, slightly bitter, and surprisingly milky'—with a distinctive texture that is firm when first cooked but yields to a mealy softness in the finish. Ginnan's most significant health consideration is ginkgotoxin (4-O-methylpyridoxine), a compound that inhibits GABA synthesis and can cause nausea, vomiting, or seizures in large quantities—traditionally recognised in Japanese food culture as a food to be enjoyed in small portions (fewer than 10 nuts per serving is the conventional guideline).

Chestnuts (kuri) hold a unique position in Japanese food culture as one of the most celebrated and ritually significant autumn ingredients, rivalled only by matsutake mushrooms and new-season Pacific saury in the emotional weight attached to their brief seasonal appearance. Japanese chestnuts (Castanea crenata—Japanese chestnut or nihon-guri) are distinct from Chinese and European varieties in their size (typically larger), sweetness, and texture. The most celebrated Japanese chestnut cultivars include Ginyose (from Tsukuba, Ibaraki—particularly prized for kuri kinton), Yamato (from Nara), and Tanba kuri from Kyoto's Tanba region, which has a centuries-long relationship with the imperial court's autumn chestnut service. The peeling challenge—chestnut's triple layer (outer bur, hard inner shell, and papery astringent inner skin or shibui)—has generated specific Japanese techniques: soaking in boiling water then cold water, or using the specialized 'chestnut peel knife' (kuritori hōchō), or the electric chestnut peeler (kurimuki-ki) for commercial volumes. Kuri kinton (chestnut sweet potato purée) is the most culturally significant preparation—one of osechi ryōri's golden items representing 'golden fortune,' made by simmering sweetened chestnuts with strained sweet potato (satsumaimo) purée until a golden paste is achieved, each chestnut piece maintaining its shape at the surface of the gold purée. Beyond kinton, kuri appears in kurigohan (chestnut rice), kuri yokan (chestnut sweet bean jelly), kuri mushi yokan (steamed chestnut bean jelly), and the French marron glacé tradition which Japan has enthusiastically adopted as autumnal luxury confectionery.

Mitsuba (Cryptotaenia japonica), the three-leafed Japanese herb, is one of washoku's most distinctive and underappreciated aromatics in global contexts. Its flavour profile is genuinely unlike any Western herb—a complex combination of fresh green celery, parsley, angelica, and a mild anise note with a subtle bitterness that functions as a palate awakener. Unlike shiso, which has gained significant international recognition, mitsuba remains largely unknown outside Japan despite being fundamental to many iconic preparations. It serves as the garnish herb in chawanmushi (steamed egg custard), where its bright green colour and clean flavour provide the traditional counterpoint to the rich savoury custard. It appears in clear suimono soups as the green aromatic added in the final seconds before service. It is folded through chawanmushi batters, stirred into clear broth with mochi for New Year ozōni, and used raw in salads and sunomono. Mitsuba is categorised by cultivation method: ne-mitsuba (root mitsuba) grown in water with elongated pale yellow stems and a more delicate flavour; kiri-mitsuba (cut mitsuba) grown in soil with dark green leaves; and mitsuba sold as bunches for general cooking. The blanched pale ne-mitsuba stems are tied into knots to garnish chawanmushi or soup—a gesture of craft and aesthetic care. Like most Japanese herbs, mitsuba is added at the very end of cooking or after—prolonged heat destroys its volatile aromatics entirely.

Japanese cuisine's relationship with native citrus extends far beyond the globally recognised yuzu to encompass a remarkable family of sour fruits, each with distinct aromatic character and seasonal availability. Sudachi—a small, intensely sour citrus from Tokushima Prefecture—is perhaps the most versatile of these native varieties. Smaller than a golf ball and brilliant green when used at peak (unripe), sudachi has an extremely high juice yield relative to size, a bright, clean, focused acidity, and an aromatic profile described as lime-meets-grapefruit with a distinctly Japanese herbaceous note. It is the canonical citrus for garnishing grilled autumn fish (sanma saury fish with sudachi is one of autumn's most iconic food pairings), for ponzu production, and for dipping soba. Kabosu, from Oita Prefecture, is larger (lemon-sized), with lower acidity than sudachi, a slightly more bitter rind, and a more complex aromatic profile—considered more versatile across seasons. Both are used primarily as juice and garnish rather than as fruit, owing to their extreme sourness when raw. Yuzu's dried zest (kibyō-yuzu) and juice are used in winter; sudachi in autumn; summer is the domain of lime and kabosu; spring brings kabayaki and the delicate new-season leaves of yuzu plants (yuzu leaves in broth). Together these citrus varieties create a complete native citrus calendar that structures Japanese cooking's acidic dimension through the year. The rind of all these varieties contains concentrated essential oils—used in broth finishing, vinaigrettes, and yakimono glazes—and their leaves occasionally serve as aromatic wrappers for steamed preparations.