Chili oil is a common ingredient, garnish and condiment in the cuisines of China and Vietnam, both for the complex and spicy flavours it imparts as well as its rich, red colour. While available in jars at most large Asian markets, chili oil is cheap and easy to make at home in whatever quantity is desired. Variations in the recipe are as numerous as households in China, and experimentation is to be keenly encouraged. The recipe below is a chili oil suitable for most Chinese dishes; the simplest omit all ingredients but chili flakes and oil.
- If a smokey flavour is desired, toast the whole peppers and Szechuan peppercorn separately in a dry frying pan over medium-heat until you can smell them in the kitchen, stirring constantly (this takes only a few minutes). Chop the peppers if used (or cut them with scissors, or crush them in a mortar and pestle). Set aside.
- Add your oil to a pot or saucepan over medium high-heat, and allow it to heat until the viscosity of the oil is reduced and the surface shimmers.
- To the hot oil, carefully add all remaining ingredients. Stir gently, lowering the heat if required to keep the oil below a simmer.
- Remove from heat once the chilis have blackened, and allow the oil to cool (the chilis will sink to the bottom).
- In higher-class restaurants in China and abroad, the oil is frequently strained or "poured off" of the layer of solids, which clarifies it somewhat; this step is optional. Many prefer the more rustic look (and texture!) of home-made oil, which will develop a darker colour over time from the solids below.
- It is important to note that, contrary to popular belief, oil is not a preservative. The seasoned oils commonly available at markets have been treated with preservatives to allow them to remain stable for a prolonged period of time. The product should be kept in the fridge (where it will keep for months) or else used within a few days and kept covered. This is particularly important if one has used fresh garlic in the oil, as harmful pathogens found in the soil garlic grows in may grow and produce toxins in the oxygen-free environment created by the oil. Leaving the oil out at room temperature also increases the likelihood that the oil itself will go rancid, though this generally takes weeks.
- Open a window or turn on a fan; if you burn the chili peppers the smoke will trigger a rather unpleasant coughing fit.
This oil is popularly used as a topping for Pho or any clear soup, dry noodle dishes, and as a sauce for dim sum. Used in stir fries, it imparts a beautiful red colour to the cooking liquid as well as a distinctive aroma. It is absolutely essential to both Szechuan and Hunanese cuisines.