01 - Place the daikon, carrots, cucumber, and bell pepper in a large bowl. If you prefer extra crispiness, sprinkle 1 tablespoon salt over the vegetables, toss, and let sit 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, stirring until the sugar and salt are completely dissolved. Remove from heat and let cool to room temperature.
03 - Layer the vegetables, chilies (if using), garlic, and peppercorns into a clean 1-quart jar or container.
04 - Pour the cooled brine over the vegetables, ensuring they are fully submerged. Seal the jar.
05 - Refrigerate for at least 2 hours before serving. For best flavor, let marinate overnight. Consume within 2 weeks.