Hi Paul! How are you? I am in Buenos Aires province, but I have eaten a couple of times the pepper you are talking about . We know it under the name of "Kitucho" or "Quitucho" ( In some places is also known as Cumbari pepper). It is a wild pepper that is manly cultivated in Salta province in the north of the country as you said, and is always eaten in oil. It is quite hot ( around 100k). It is very small, like half of a blueberry.
I have sown some seeds this year for the first time, but with no results yet.
Hope it helps!