In a large stainless steel saucepan, heat the rice vinegar, sugar and 1 teaspoon salt over medium heat until the sugar dissolves, about 5 minutes. Add the carrot, celery, onions, garlic, chiles and peppercorns. Cover and simmer over medium-low heat for 30 minutes. Remove from the heat and let cool to room temperature. The pickled vegetables can be refrigerated in an airtight container for up to 2 weeks.