Peel the Chinese radishes. Rinse it in cold water and dry it with a clean kitchen towel. Cut the Chinese radishes into 2 - 2.5 cm thickness and place them in a bowl. Add sugar and salt and mix well. Let it rest for 30 minutes. Remove the juice/liquid from the bowl and save it in a small bowl. Add chopped garlic, chopped ginger, chopped chives, fish sauce, chili flakes, and juice from the radishes. Mix everything so that the spices are well distributed. Place everything in a pickling jar and press everything together well to avoid air between the radish pieces.  Put the lid on the jar. It can be eaten immediately and should be stored in the refrigerator. However, you can keep it outside the refrigerator (keep it away from direct sunlight) for a few days. It will then begin to ferment, and you will see bubbles on the top. Make sure to open the lid briefly and close it again once or twice a day to avoid pressure buildup in the jar. It will start to smell a bit strong and sour. After this, it should be stored in the refrigerator but can also be eaten immediately.