Finely chop the red peppers, garlic and chiles in a food processor.
Transfer the mixture to a sieve and strain out the liquid as much as you can.
Heat oil in a pan and add the strained liquid. Let the liquid reduce on low heat for 12-15 minutes. Keep stirring and season with salt.
Once it has reduced and has a slight paste-like consistency, take it off heat, allow it to cool down and then use or store for later.
Notes
Increase or reduce the amount of chilies in the recipe depending on your tolerance for heat. If you want the paste to have a mildly spicy flavor, add just a few chilies.
You can also cut down the heat by removing the seeds and the white pith in the center of the chilies before you process them.
To get the Biber Salçası to have a more thick, pasty consistency, pour the reduced mixture in a baking dish and pop it in an oven preheated at the lowest setting. Allow this to cook for 10-30 minutes, and check occasionally to see when it starts to dry up and turn thick.
Make sure you wear gloves while handling the hot peppers.