Nasu cultivation in Japan dates to the Nara period (710–794 CE) — one of Japan's oldest cultivated vegetables; the Japanese variety was developed through centuries of cultivation from South Asian wild eggplant varieties; Kyoto produces specific heritage varieties (Mizu-nasu — water eggplant, so tender and mild it is eaten raw; Kamo-nasu — the large round Kyoto eggplant used for dengaku); the Shibazuke pickle (a Kyoto specialty) uses eggplant as the primary ingredient
Japanese nasu (茄子 — eggplant, also called aubergine) is a distinctly different ingredient from the large Mediterranean or South Asian eggplant — a slender, deep purple variety (10–15cm long) with thin skin and minimal seeds, producing a tender, quickly cooked vegetable with a delicate flavour that absorbs oil and seasoning readily. The Japanese eggplant's thin skin eliminates the need for salting and pressing to remove bitterness — a requirement for larger seeded varieties but unnecessary for the Japanese type which is almost entirely flesh. The definitive preparations: dengaku (scored surface, grilled and topped with sweet miso glaze — white or red miso with mirin); shigiyaki (similar to dengaku but with miso cooked into the eggplant rather than added as glaze); yakinasu (whole eggplant charred over direct flame or gas burner until the exterior is completely blackened and the interior steams to a smoky, creamy consistency — served peeled with dashi-soy and grated ginger); agebitashi (flash-fried eggplant, plunged into cold dashi to absorb flavour — a cooling summer preparation); and simmered in miso broth. Yakinasu is the most technically specific: the whole eggplant must be placed directly on a gas flame for 8–10 minutes until completely charred outside and collapsing inside — the charring produces the key smoky component.
The yakinasu's smoky character is one of the most complex flavour profiles in Japanese vegetable cooking: the charring of the outer flesh and skin produces pyrazines, guaiacol, and phenol compounds from incomplete combustion of the cellulose and lignin; these volatiles penetrate the steaming interior and combine with the eggplant's natural 5-alpha-cholestanone (a slightly sweet compound) and chlorogenic acid; the result is a flavour with smoke, sweetness, and delicate bitterness that has no equivalent in any other vegetable preparation method
Thin skin means no salting necessary; scored surface accelerates oil penetration and flavour absorption; yakinasu requires complete exterior charring for the interior steaming effect; agebitashi technique (fry then immerse in cold dashi) creates deep flavour absorption through thermal shock; nasu's sponge-like interior absorbs whatever medium it is cooked in — requires deliberate control of the absorbed flavour.
Yakinasu technique: hold whole eggplant directly in a high gas flame using tongs, rotating every 90 seconds for 8 total minutes; the exterior will completely blacken and the eggplant will shrink and soften; hold under running cold water while peeling the charred skin — the skin separates easily; squeeze gently to release excess water; serve with dashi-soy and katsuobushi; the smoky quality of yakinasu is a direct Maillard product from the charring of the outer flesh; agebitashi: fry scored eggplant halves in 180°C oil for 90 seconds skin-down, then 30 seconds flesh-side; immediately immerse in cold dashi-mirin-soy mixture; rest 30 minutes before serving.
Salting Japanese nasu (unnecessary — no bitterness from seeds; the salt draws moisture and softens the structure too much); insufficiently charring yakinasu (a lightly charred exterior doesn't steam the interior or develop the signature smokiness); overcooking in oil (becomes oil-saturated and greasy rather than absorbing just the surface layer); not scoring before dengaku glazing (miso glaze doesn't penetrate unscored surface).
Tsuji, Shizuo — Japanese Cooking: A Simple Art; Murata, Yoshihiro — Kaiseki