I'll start with the easy, quick links and describe more afterwards. Check out
Guatemalan Black Beans: Part I and
Guatemalan Black Beans: Part II. These are written in English by a Guatemalan woman now living in the U.S. (apparently upstate NY) and they pretty much agree with what I read on Spanish-language sites from Guatemala.
Now for a little more detail: According to the blog
Chapina Hasta el Hueso (literally, "Guatemalan to the bone"), written (in Spanish) by a Guatemalan woman now living in Uruguay, there are three main ways that black beans are served in Guatemala.
The first is "
Parados" or whole (literally "standing"). For these, you chop up and brown an onion, then cook the beans in that (she doesn't give more details or an actual recipe, but the first link, above, covers that). She also says that some people use olive oil, some use chiles, and so on.
The second is "
Colados" or strained (a few other sites referred to these as "
Licuados or "liquefied" - i.e. puréed in a blender). She says, "Since mothers usually use a pressure cooker to make four pounds [of beans at a time], after three days, the charm of the whole beans wears off, so you proceed to the second stage: put the beans into the blender, throw in a little water and out come the
frijoles colados. They may also go through the process of frying with some browned onions and eating them, puréed and very smooth, with French bread and lots of
crema or topped with
Quesito de Zacapa (a dry, Parmesan-like cheese), onions and parsley."
The third is "
Volteados" or refried (literally "turned"). She says, "Then, just when it seems absurd still to be eating beans, mother masterfully spends three hours in the kitchen, turning and flipping, then brings out to us a tray with a
maleta (literally "suitcase" - just what they colloquially call the log shape in which the beans are presented) of refried beans. For me, this is the most delicious stage of the beans. You eat these with
queso fresco, and fried plantains on the side."
As I said, this represents the basics and everything else I found agreed with the above and is covered in the two English-language links at the beginning of this post. Otherwise, there were only a few minor differences, such as whether or not to use garlic, one that suggested adding some adobo seasoning, and others saying to add other spices according to your taste.
P.S.: Just called the owner of the hotel where I stay in Guatemala to let him know that I won't be able to go there next month. While I had him on the line, I asked about the black beans and he said that what everyday people usually make is just with onions, garlic and salt. Of course, in a restaurant, they may jazz it up a bit, so I can't say what you may have had at the restaurant, but the links above do give the basics accurately.