Pao Jiao (泡椒, pao jiao), known as Sichuan pickled chili pepper, is a small, sour, and spicy pickled pepper used in Sichuan cuisine. The flavor is less spicy than that of fresh chili pepper but spicier than that of bell pepper. You can find both green and red pao jiao.
Pao jiao is edible by itself. It can be added into stir-fries, salads, and marinades for some extra flavor. A good example of a dish that uses pao jiao is the famous Sichuan dish xu xiang rou si (fish fragrant shredded pork stir fry).
You can find pao jiao in a jar in Chinese market. You could also use Cajun pickled pepper or pickled jalapeno as an alternatives.