The smell is a bit like sauerkraut and chile mixed together. It has a crunchy-tender texture, like cucumber pickles, with a salty, sour, spicy taste. Different brands may emphasize one taste more than the other.
It is used as a flavouring ingredient in many dishes; it can also be thinly sliced and served room temperature as a starter.
To make it, the thick stem of the plant is peeled, sliced into thick chunks, then salted and pressed and dried. It is then coated with hot red chile paste, and allowed to allowed to ferment in a pottery jar.
Hot-Pickled Mustard Root is sold sold whole, shredded, sliced, flaked or broken, either in cans or in sealed plastic pouches. There are also some low-salt versions available now.
Not the same as Pickled / Preserved Mustard Greens.
When using Hot-Pickled Mustard Root as an ingredient, it is generally sliced into thin strips or shredded or chopped finely, then rinsed or soaked first to remove excess salt and chile paste. If soaking in water, recipes seem to call for 20 to 30 minutes.
This pickling technique was developed in Szechuan, China. Fermenting food in a spicy sauce helped to preserve it in Szechuan’s hot climate.
Aka “Szechuan Vegetable”, but that is quite vague and unhelpful. Aka Cha Tsai.