Salsa arriera is a traditional sauce originating from Central Mexico. This mouth-searing salsa is usually made with a combination of serrano chili peppers, chopped white onion, garlic, salt, and a few tablespoons of cold water. The chili peppers are toasted on a comal or a griddle and occasionally turned until they become charred and blistered.
While still hot, they are ground with the other ingredients into a rough paste. The process is typically done in a molcajete. The name salsa arriera means mule driver's sauce because it is believed that the salsa was famously eaten by mule drivers.