What is corn mix?
I think it's corn meal. Like flour, but from corn, not wheat.
It can be found in your flour section. It's used to make corn tortillas. Masa Harina is a brand name.
It's really "dough mix," like Bisquick for tortillas. Yikes, you probably don't know Bisquick, either.
Masa harina, translated literally, means corn flour, but it's really finely ground hominy - or dried posole. It has been through a lye treatment process that makes it taste quite different from corn - and it's *not,* I repeat, NOT, your "corn flour," which is our cornstarch.
The texture is nothing alike and the taste is nothing alike. Masa harina tastes like something! Like wet tortillas!
Can you get dried posole or dried hominy there - even grits? If you have a way to grind (would need to be an almost commercial-strength grinder) it, you might be able to get close.
You could also try grinding very finely some regular cornmeal - like you make porridge or cornbread with. Do you have cornmeal, called as such?
You make pone, or corn sticks, or hush puppies, or "mush" with it. Do you know it?