Masienda , the heirloom corn folks, are now selling tortillas made from nixtamalized, heirloom corn at selected grocery stores in the U.S. , mostly Whole Foods. In San Diego it appears they are only available the WF in Del Mar.
I think all commercial tortillas are made from nixtamal. The special thing about these is the sourcing of heirloom varieties.
Most commercial tortillas are made from reconstituted masa harina from Maseca (which owns Mission and Guerrro brand tortillas in the U.S) . From what I understand, the process Maseca uses to produce masa harina does not rely on nixtamalization of corn.
Oh, right, some of those national supermarket brands are weird fake crap.
Where I shop the ingredient list on most brands of corn tortillas is “Corn, water, lime,” lime as in calcium hydroxide, used to nixtamalize the corn.
Arellano is more optimistic. He says lots of tortillerias and mercados where he lives, in Southern California, undertake the masa process from scratch, and that your absolute best option is to find one near you.