What is this Vietnamese Food?
Does it look like this?  I have some in my pantry now.  (Don't tell anyone.)

By request, the box contents: inside a cellophane sleeve, 4 foil-wrapped cubes.  Here's one:

Texture is very much like a boullion cube - hard, with a bit of sticky give when pushed.  Salty, as expected, but also sweetish with a distinct flavor of caramelized onions and star anise.