Add all ingredients except for the olive oil into the work bowl of a mini food processor. Process until the cilantro is very finely chopped and the mix has a light green color (about 1 minute). Scrape down the sides with a rubber spatula, if needed.
With the blade running, slowly pour in the olive oil.* Process until smooth.
Recipe notes:
*Most mini food processors have a so-called "drizzle basin" in the lid that lets oil drip through slowly while the blade is running. If your food processor doesn't have such a feature, simply add the oil into the work bowl all at once. Then put the lid back on and continue to process until smooth (about another 10 seconds).Storage: Store this sauce in an airtight container in the fridge for up to 4 days.