Ah, they're not meant to be burger buns specifically. They're a bit small for that. The dough balls weight 45 grams a piece. Pan de sal literally means salty bread. The name is deceiving though as the ingredients include both sugar and salt. Think brioche when it comes to texture.

I know. I make it all the time and use it for sliders. Or make it bigger and use it for regular sized ones. Less sweet than American buns, holds up better to juices, and the salty kick is a perfect balance to the sweet.