Heat oil in a large skillet or saucepan over medium-high heat. The oil should be hot enough so that when a pepper is dropped into the skillet, it will immediately start to sizzle.
Add the ancho chiles and pan-fry for 45 to 60 seconds, stirring constantly, until nice and toasty. Be careful not to over-toast and burn them! Using a slotted spoon, quickly transfer the peppers to a large plate and set aside.
Add the guajillo and arbol peppers to the skillet. Pan-fry for 45-60 seconds, stirring constantly, until toasted. Be careful not to burn them! Transfer the peppers to the same plate using a slotted spoon.
Add the onions to the skillet and pan-fry for 1 minute. Transfer the onions to the same plate using a slotted spoon.
Last but not least, add the garlic cloves to the skillet and pan-fry for 30 seconds. Transfer the garlic to the same plate and remove the skillet from the heat.
Transfer the pan-fried chiles, onions, and garlic to a large blender. Add water, apple cider vinegar, peanuts, salt, and black pepper. Carefully pour in any remaining oil from the skillet that was used to pan-fry the chiles.
Blend until smooth. Serve immediately or store in an airtight container in the fridge for up to a month.
Notes
If the dried peppers appear dusty and dirty as can sometimes happen depending on how they're stored before selling, give them a rinse under running water before using them.
Any vegetable oil used for frying works. Avocado oil, canola oil, and peanut oil are all great options.
I recommend leaving the seeds from the chiles in the salsa. If they fall out when removing the stems, just save them on a plate and add them into the blender when it’s time to blend the salsa.
This salsa is a medium-hot spice level. To make it a little milder, use 2-4 arbol chiles instead of 6. Or use 8-10 arbol chiles to make it spicier.
If you don’t have peanuts, you can use almonds instead. I recommend toasted/roasted almonds if possible.