Rinse the garlic chives, cut into 2-inch lengths, peel and cut the radish into matchsticks, and julienne the carrot. Combine all in a mixing bowl.

Sprinkle the gochugaru chili flakes over the vegetables, and toss until all are evenly coated.

In a saucepan, combine rice vinegar, water, sugar, salt, and fish sauce or soy sauce. Heat until sugar and salt dissolve, then cool for 15-20 minutes.

Pack the vegetables into a wide-mouth jar, pressing down to eliminate air pockets.

Pour the cooled brine over the vegetables, ensuring all are covered and release any air bubbles.

Seal the jar and refrigerate for at least 24 hours, preferably 2-3 days for best flavor.