Cut the cabbage into quarters lengthwise, remove the hard core, and chop into 1-inch wide strips.
Rinse under cold water and place in a large bowl. Massage the salt into the cabbage and let sit for 3 hours, stirring halfway.
Drain the cabbage and rinse twice under cold water.
Transfer to a mixing bowl and add the sliced daikon radish and scallions. Toss to combine.
In a saucepan, heat water, sugar, and sweet rice flour until slightly thickened.
Remove from heat and stir in the gochugaru, vegan fish sauce, garlic, and ginger to form a paste.
Coat the cabbage mixture with the chili paste thoroughly.
Pack the mixture into two quart jars, leaving space at the top for expansion, and add some reserved brine. Cover loosely to allow for fermentation.
Store jars in a dark place at room temperature for 48 hours, checking and pressing the cabbage back into the brine if needed.
After 48 hours, refrigerate the kimchi for additional flavor development. For the best taste, let it mature for a week in the fridge. It can last up to 4 weeks.