Bossam kimchi

Step 1: Clean the storage container: wash a glass jar or lidded box in hot soapy water, rinse, then dry it upside down in a 250°F oven for 10 minutes (or pour boiling water through it and air-dry). Let it cool; everything that touches the kimchi must be clean and dry. Use a container big enough for 12 parcels in one or two layers.

Step 2: Cut the 1 napa cabbage in half lengthwise through the root. Dissolve 200 g of 10 ½ oz coarse sea salt in 8 ¼ cups water (a 10% brine) and dunk both halves in it, then sprinkle the remaining salt between the leaves, mostly on the thick white stems.

Step 3: Leave the cabbage cut side up for 8 hours (or overnight in a cool room), turning it halfway. It is ready when a thick stem bends without snapping.

Step 4: Rinse the cabbage under cold running water three times, separating the leaves, and taste a stem: it should be pleasantly salty, not harsh. Drain cut side down in a colander for 1 hour.

Step 5: Whisk 1 tbsp glutinous rice flour into ¾ cup water in a small pan and cook over a medium heat, stirring, until it thickens into a glossy, translucent porridge, about 5 minutes. Cool completely.

Step 6: Toss 14 oz Korean radish (mu) or daikon with 1 tsp fine sea salt and leave 20 minutes until it bends, then squeeze out the liquid with your hands.

Step 7: Stir 4 tbsp gochugaru (Korean chilli flakes) into the cooled rice paste and let it bloom 5 minutes, then mix in 8 garlic cloves, ½ oz fresh ginger, 2 tbsp salted fermented shrimp (saeujeot), 3 tbsp fish sauce and 1 tbsp sugar.

Step 8: Add the squeezed radish and rub the seasoning in with gloved hands until evenly red.

Step 9: Gently fold in 1 Korean (nashi) pear, 8 peeled chestnuts (save a few slices for topping), 6 dried jujubes (red dates), 1 ⅜ oz minari (water dropwort) and 4 scallions. Fold in 5 ½ oz very fresh shucked oysters only if using them and everyone eating is a healthy adult; rinse them first in cold salted water and drain well.

Step 10: Pick out the 24 largest outer cabbage leaves for wrapping. Cut the remaining inner leaves and hearts into 4 cm pieces and mix them into the filling.

Step 11: Line a small rice bowl with two crossed outer leaves, stem ends in the middle. Spoon in about 1/12 of the filling, press it down and top with a few 2 tbsp pine nuts and the saved chestnut slices.

Step 12: Fold the leaf tops over to close the parcel, lift it out and place it, seam down, in the container. Repeat to make 12 parcels, packing them snugly.

Step 13: Stir 1 tsp fine sea salt into 1 ¼ cups water with any juice left in the mixing bowl and pour it round the parcels. Press a piece of baking paper on top and close the lid.

Step 14: Leave at cool room temperature (15–64°F) for 1 day until small bubbles appear, then refrigerate. Eat within 2 weeks, or within 3 days if you added oysters. Normal: tangy smell, cloudy pink juice, light fizz. Discard if you see fuzzy or coloured mould or it smells rotten or feels slimy.

Step 15: To serve, lift one parcel into a shallow bowl with a clean spoon, open the leaves at the table and spoon some juice over.