In the same wok, add 2 tablespoons of vegetable oil. Add the dried red chilies and Szechuan peppercorns, stirring until fragrant, about 1-2 minutes. Add the minced garlic and ginger, stirring for another 30 seconds. Add the sliced onion, bell peppers, and celery. Stir-fry the vegetables for 3-4 minutes until they are slightly tender but still crisp.