Mt first thought was Taraxacum as well, but there is the FOC key; <http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=20701> you can attempt to use to get it to genus. It may be one of those many other lactiferous Asters. If it has hollow scapes it should be Taraxacum.
If the image route is easier then search online for the recent Flora of Mongolia. It has a large list of Taraxacum, some of which have images you can look at.
Aaron