dongchimi brine
The clear, gently sour brine from dongchimi, a Korean radish water kimchi; cool, salty and faintly fizzy.
Dongchimi brine is the liquid in which whole or roughly cut radishes ferment slowly in the cool with salt, garlic, ginger, spring onions, pear and mild chillies over days or weeks. Unlike red kimchi it stays pale and clear, tasting mildly salty, freshly sour and slightly sweet, and the fermentation often gives it a light fizz. That cool, refreshing sourness is what makes it the base for cold noodle soups and a companion to heavy or dry dishes. It is always used cold, since heating destroys both the fizz and the freshness. Ready-made dongchimi with its brine is sold in the chilled section of well-stocked Asian grocers and sometimes by mail order; made at home it takes about one to two weeks.
Substitute:
There is no true equivalent, because the flavour comes from fermentation. The closest is the brine of nabak kimchi, another water kimchi, though it is redder and spicier. Ready-made cold noodle broth from an Asian grocer makes a usable soup but tastes more of vinegar and beef stock than of fermented radish. Lightly salted water with rice vinegar, a little sugar and grated radish catches the sourness, but not the depth or the fizz.