Wash and quarter the cabbage, discard the core and slice across into 2.5cm strips. Place in a bowl with 2 tablespoons sea salt and massage gently the leaves until fully covered in the salt. Cover and set aside for 1 hour.
Whisk together the chilli paste, vinegar, sugar, garlic, ginger and fish sauce and make a smooth paste.
Rinse the cabbage thoroughly under cold tap water and drain well, squeezing out excess water. Place in a clean glass bowl along with the carrot, radish, spring onion, chives, and chilli paste. Put on a pair of clean rubber gloves and mix well, until all the vegetables are mixed in the chilli paste.
Pack into a 1 litre Kilner jar with a non-reactive top, leaving a few centimetres head space. Ferment at room temperature overnight before transferring to the refrigerator for a few hours. You can eat the kimchi immediately, but the flavours will continue to develop. Consume within 2 weeks.