yuzu kosho resembles a thick relish or spread and is a powerhouse of flavor. Chili peppers and salt are typically the only other ingredients accompanying the citrus zest to make this condiment.
The umami flavour of miso paste works really well with aubergines; the ‘meaty’ flavours are lifted by the fragrant citrus sharpness of yuzu ... Mix all the marinade ingredients together ...
There isn’t a substitute for it, but if you can’t find it at your local Japanese market (where you can also buy bottled yuzu juice), use light soy sauce diluted with some water to taste.