Wash the cabbage well, chop it into bites and place it into a big bowl with water and salt.
Toss the cabbage well in the salted water, place a weight on top and set aside for 1 hour and half, stirring it every half an hour.
In the meantime cut into matchsticks (julienne) the daikon, the carrot and the spring onion. Add the chopped veggies to the cabbage in the last half an hour.
In a bowl combine the Gochujang paste, the garlic, the ginger, the soy sauce and the mushroom sauce.
Rinse the cabbage and the vegetables well with fresh water, then squeeze well and pat dry with a cloth to remove all the liquid.
Transfer into a clean bowl and pour over the spicy paste.
Toss and squeeze the veggies well in the sauce (it's better if you use some gloves).
Transfer to a serving dish and serve immediately. If you like you can sprinkle with some roasted sesame on top of the kimchi.