Cut the cabbage lengthwise through the stem into quarters. Cut the cores from each piece. Cut each quarter cross-wise into 2-inch wide strips.
Place the cabbage in a large bowl and sprinkle with the salt. Using your hands, massage the salt into the cabbage until it starts to slightly soften. Add enough water to cover the cabbage and leave for 30 minutes.
After 30 minutes, place the cabbage in a colander and set aside to drain.
In a bowl, add the garlic, ginger, sugar, sriracha, tomato paste or sweet chili paste, and water. Stir to form a smooth paste.
Gently squeeze any remaining water from the cabbage and add it to the spice paste. Add the radish and scallions.
Mix thoroughly, using your hands to gently work the paste into the vegetables until they are thoroughly coated and serve. Refrigerate for at least 24 hours or up to 3 days in advance.
*Tip: use powder free latex or vinyl gloves to mix the kimchi together.
Notes
Pro Tip - start the kimchi first before starting the rest of the meal. This can also be made days in advance if you desire a more fermented kimchi.