Gundruk

Step 1: Spread the 2 ¼ lb mustard green leaves and 1 ⅛ lb radish leaves on a mat or clean sheet in an airy place out of direct sun and let them wilt for 1–2 days, turning once, until soft and limp but not yellow.

Step 2: Wash a 2 litre glass or ceramic jar with hot soapy water, rinse, then set it upside down in a 250°F oven for 10 minutes; let it cool.

Step 3: Shred the wilted leaves roughly and pound or crush them a handful at a time in a mortar or with a rolling pin until bruised and juicy.

Step 4: Pack the crushed leaves into the jar in layers, pressing each layer down hard with your fist until liquid rises above it. If, after packing, no juice covers the top, add the ½ cup lukewarm water.

Step 5: Set a small weight (a water-filled zip bag or a clean stone in a bag) on top so the greens stay under their juice, close loosely and keep at 20–86°F for 7–10 days.

Step 6: Check every day. Normal: bubbles, cloudy brown liquid and a clean sour smell; a flat white film (kahm yeast) can be skimmed off. Bad: fuzzy green, black or pink mould, slime or a putrid smell — throw it all away. It is ready when it smells sharply sour and the leaves are olive-brown.

Step 7: Squeeze the greens and spread them thinly on clean mats or trays in strong sun for 3–5 days (or in a 122°F oven with the door ajar for 6–8 hours), turning daily, until completely dry and brittle.

Step 8: Store in an airtight jar in a cool, dry place for up to a year. Throw away any that smells musty or shows mould. To cook, soak a handful in warm water for 10 minutes and simmer into soup or toss into a salad.