Combine the cabbage, daikon, and carrot in a large, non-reactive bowl.

Dissolve the salt in the water and add to the bowl. Stir to gently submerge the vegetables. Use a plate with a weight on top to hold down the vegetables and soak overnight.

Drain the vegetables well, reserving the brine.

Add the garlic, ginger, scallions, and gochugaru to the vegetables and mix well. Pack into a quart-size jar, pressing down to release the brine so it covers the vegetables (add reserve brine if necessary).

Add a freezer bag filled with reserved brine to the jar to keep the vegetables submerged. Loosely cover to allow gas to escape.

Ferment in a dark, room temperature location for at least 4-7 days, then store in the refrigerator.