Sichuan chilli oil (红油, hong you, literally red oil) is the foundational condiment of the Sichuan kitchen — used as a cooking fat, a finishing drizzle, a sauce base, and a dipping condiment. It is made by pouring very hot oil over dried chilli flakes and aromatics, releasing fat-soluble pigments and aromatic compounds into the oil. The depth of a chilli oil is determined by the quality and variety of dried chillis used, the temperature of the oil when poured, and the aromatic additions.
The core technique: Place 30g dried chilli flakes (ideally a mix of facing heaven chillis and er jing tiao chillis), 1 tsp Sichuan peppercorns, 1 tsp sesame seeds, and optional aromatics (star anise, cinnamon, bay leaves) in a heatproof bowl. Heat 120ml neutral oil to 160-180C. Pour the hot oil over the spices in 3 stages — initial pour at 180C (blooms the spices), second pour at 160C (extracts color), third pour at 140C (final extraction). Stir after each pour. Cool completely. Add 1 tbsp soy sauce and 1 tsp Chinkiang vinegar to balance. Chilli varieties for hong you: Er jing tiao (二荆条) — the standard Sichuan dried red chilli, medium heat, excellent color. Facing heaven chilli (朝天椒) — hotter, used for heat depth. Combine both for complexity. The temperature gradient matters: A single pour at too-high temperature burns the chilli. A single pour at too-low temperature fails to extract color and aromatic compounds. Three staged pours solve both problems.
Lao Gan Ma (老干妈) crispy chilli oil is the most famous commercial chilli oil and is an acceptable substitute in many dishes, though it contains additional ingredients (soybeans, preserved vegetables) that alter the flavour profile. Homemade hong you keeps refrigerated for 2-3 months. The oil on top (above the settled solids) is the most refined expression; the sediment-rich oil from the bottom is more intense.
Using generic chilli flakes: Korean gochugaru, Italian peperoncino, and dried cayenne lack the specific aromatic profile of Chinese dried chillis. Single-temperature pour: Either burns the spices or fails to extract full color and aroma.
Fuchsia Dunlop, The Food of Sichuan (2019); Fuchsia Dunlop, Every Grain of Rice (2012)