First you’ll have to make the tezu – the vinegar-water pickling liquid. Conveniently, this is the same dressing you’ll use to season your quinoa, so the amounts below are in fact enough for both the pickled ginger and rolls. Use half measures if you are only making the pickled ginger. Whisk together. Set half aside to dress the quinoa.
Peel the ginger and slice it thinly on a mandolin, grater or exercise your awesome knife skills.
Sprinkle the ginger with salt, toss to coat, and let it sit for 30 minutes.
Using your hands, squeeze the whole lot of ginger out over a sink, rinse well with cold running water and squeeze out again until it is as dry as possible.
Soak the ginger in a glass jar with half of the tezu (it should be submerged; if not add a little more). Let marinate for 15 minutes. Serve.
Cover and store leftovers in the fridge for up to 2 weeks.