This is one of the perennial street snacks sold all around Oaxaca City. Eventually I was able to reproduce it from memory. The peanuts used there are a larger variety, but the taste is identical. Be sure to use a medium-coarse salt like kosher salt. The garlic is peeled and eaten along with the peanuts.
Though strictly speaking this should be served hot, I confess that when I started nibbling on a bunch of room-temperature leftovers, they were so delicious I couldn’t stop.