01 - Place the daikon, carrots, cucumber, and bell pepper in a large bowl. For extra crispiness, sprinkle 1 tablespoon salt over the vegetables, toss thoroughly, and let stand for 15 minutes. Rinse under cold water and drain well.
02 - In a small saucepan, combine rice vinegar, water, sugar, and salt. Heat over medium heat, stirring constantly until sugar and salt are completely dissolved. Remove from heat and allow to cool to room temperature.
03 - Layer the vegetables, chilies if using, garlic slices, and peppercorns into a clean 1-quart jar or container, pressing down gently to compact.
04 - Pour the cooled brine over the vegetables, ensuring they are completely submerged. Seal the jar tightly with the lid.
05 - Refrigerate for at least 2 hours before serving. For optimal flavor development, marinate overnight. Store refrigerated and consume within 2 weeks.