As an American, I can honestly say that this restaurant has the best burgers I've ever had. I stayed in the small Seventh-Day Adventist village of Libertador San Martin, whilst studying abroad for Spanish. In place of the standard sesame bun, they replace it with a fluffy ciabatta-like bun that is so light (and they bake it fresh). The quality of beef is 100%, so soft and tender that one could still eat it even without teeth. I usually ordered "original completa" with fries. Search them on FB for full business hours.
****NOTE: they're closed on Fridays******
Find them on instagram: @lapasteurresto - you can DM to order read more