Preheat a large pot of water, bringing it to a boil. Place a large bowl of ice cold water to the side (for blanching).

Remove the stems from the chilies, cut the peppers in half, then remove the seeds as well.

In a frying pan or skillet over high heat (no oil), toast the chili halves for approximately 3 minutes.

Remove the chilies from the pan and drop them in the boiling water. Allow the chilies to boil for 3 minutes.

Remove the chilies from the boiling water and place them immediately in the ice cold water. Let them sit until all heat is removed from the chilies (1 to 2 minutes).

Remove the chilies from the cold water and place them in a food processor with the vegetable oil. Process the aji until you reach your desired paste consistency.

Place the paste into a sealable jar and serve immediately or, for best flavor, cover the paste and let it refrigerate over night to allow the flavors to meld.