Gochugarualso: Korean red pepper flakes
Sun-dried Korean red pepper, ground to a coarse flake. The visual and flavour signature of kimchi, gochujang, and tteokbokki.
Origin
Korean. Capsicum arrived in Korea in the late 1500s via Japanese trade with the Portuguese; gochugaru as we know it was standardised in the 1700s. The best comes from Yeongyang in North Gyeongsang province.
What it tastes like
Smoky, fruity, mildly sweet. Heat is moderate (Scoville ~4,000–8,000) — much less than cayenne. Not interchangeable with chili powder.
How it's used
Kimchi (the red colour is exclusively gochugaru). Mixed into doenjang for ssamjang. Sprinkled on grilled meats. Used in 90% of Korean stews and braises.
Buying
Buy from a Korean grocery if possible; supermarket 'Korean chili flakes' are often the wrong product. Look for vivid red-orange colour and a fruity smell. Refrigerate after opening.
Substitutes
If absolutely necessary, a 70/30 blend of mild Hungarian paprika and cayenne approximates the colour and heat. The smoke and sweetness are lost.
Storage
Refrigerator or freezer, sealed, 6–12 months. The colour fades in light.