I went to Mongolia for a month with Zavkhan trekking. I highly recommend them.
We had a support truck that carried most of the supplies (even the live sheep we bought a long the way!). It was a blast! Did not have the tummy troubles, but did eat weird combinations of every day food. (Pickles in your soup? Right next to that sheep’s head!)
There was butter, but no steaks, just everyone’s favorite, fried bread! That was named something that sounded (and sort of looked like) like “ballsack”. It was delicious.
I thought the accomodations were pretty damn lux, myself, but I’ve lived in a house with a composting toilet, so I may not be average.