Prepare enough chard to fill the preserving jar almost to the top, tightly packed in. Test the fit and weigh the chard. Prepare the dill, garlic, ginger, and chilli but keep separate; weigh these as well, then set aside.
Measure out 2–3 per cent of the total weight in salt.Place the chard in a large bowl and sprinkle over the salt. Massage the salt into the chard, until it begins to release beads of water and starts to soften. Leave for a couple of hours to let osmosis take effect.
Place the salted chard and any juices into a 1 litre jar, scattering over the herbs and spices with each handful.Pack in the vegetables tightly, pressing them down as you go and eliminating air pockets between layers.
Use a pestle or the end of a rolling pin to tamp down the ingredients.
Top up the jar with water, if needed, so that the vegetables are submerged. Cut a disc of baking parchment large enough to cover the contents of the jar, with some excess.
Place the disc over the vegetables, pressing it down and into the edges to ensure the surface is completely covered.
Seal the jar and date and label the contents. Leave to ferment at room temperature, out of direct sunlight, for 1–2 weeks.
Taste regularly after 1 week, until the preferred degree of sourness is reached, then transfer to the fridge, where it will keep for several months.