1. Stir salt into 2½ cups water in large nonreactive bowl. Add cabbage, and stir to coat leaves well. Let stand 5 hours, or overnight, stirring occasionally. Drain.
2. Grind chiles in coffee grinder until powdered (it’s OK if there are some larger bits).
3. Transfer cabbage to clean bowl, and add 1½ Tbs. ground chiles, radish, green onions, rice vinegar, garlic, ginger, and sugar. Toss with hands (wearing rubber gloves) to coat. Transfer to clean 1-quart canning jar, packing cabbage tightly. Seal with lid. Let stand 2 to 3 days at room temperature, turning upside down occasionally to coat cabbage with pickling liquid. Store in fridge up to 2 weeks.