Slice the Napa cabbage into 1" squares and separate the leaves. Mix well with 3 tbsp salt until evenly covered, and leave to sit at room temperature for 1.5-2 hours. Toss every 15-20 minutes. The cabbage will reduce in volume, release water and soften.

Next wash away the salt: fill the bowl cabbage bowl with cold water and then drain. Repeat several times.

In a separate bowl, mix the red pepper powder with the fish sauce, water, ginger, garlic and spring onion and pour over the cabbage. Massage into the cabbage well for a minute using your hands. The cabbage will release some more liquid, but try not to bruise it.

Move the cabbage mixture into a clean 3 litre clip-top jar. Press down well with a clean fork or your fingers to remove air bubbles, pushing the cabbage beneath the liquid. To help keep the cabbage submerged you could also place a tiny sauce-dish inside the jar pressing on the cabbage.

Close the lid and leave at room temperature to ferment for 48 hours (at around 20 degrees Centigrade). Whilst the cabbage is at room temperature, you must open the jar every 12-24 hours to release any gas build up and push the cabbage back under the liquid.

After 48 hours your kimchi will be ready to eat!

Move it to the fridge, and consume within a few weeks.