01 - Place the daikon, carrots, cucumber, and bell pepper in a large bowl. For extra crispiness, sprinkle 1 tablespoon salt over the vegetables, toss, and let sit for 15 minutes. Rinse thoroughly 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, and peppercorns into a clean 1-quart glass jar or container, packing them tightly.
04 - Pour the cooled brine over the vegetables, ensuring they are completely submerged. Seal the jar tightly and refrigerate for at least 2 hours before serving. For optimal flavor development, marinate overnight. Store refrigerated and consume within 2 weeks.