Egyptian pupusas?! I can do it if I find a masa substitute!

Hi everyone!

Four summers ago I discovered Salvadorean cuisine at the lovely Balompié in SF, and I've loved pupusas ever since. Thing is, I live in Egypt and there's nowhere here I can get my fix.

Today, however, I was feeling energetic, and I decided to try making my own. I blithely skimmed through the ingredient list for pupusas, curtido and salsa roja, and was thrilled to see they were all available here (substituting Egyptian ful medammes for frijoles of course!).

The table was laid with dishes of salsa and curtido and everything was going perfectly when, as I started kneading the dough, I got a funny feeling something wasn't right. I put it down to my being a novice and ploughed on, but when I started frying my "pupusas", I could see something was definitely up. It was at this point that I consulted the internet and found out that corn flour was absolutely not the same thing as masa harina. Ah. Anyway, the result was not inedible (I've christened them polentusas) but I would quite like to be able to make actual pupusas sometime rather than starchy cornbread balls.

So to get to the point, I am looking for a masa harina substitute. Let me make this clear before someone suggests I try my local Mexican store: I definitely, categorically, cannot get masa harina here in Cairo. I also cannot get corn tortillas which I could grind up as a substitute. It's also not an option to make my own from scratch, at least for now, because I'd need someone to bring me cal mexicana from the US (and now I come to think of it I don't think I can get the right kind of corn here).

Question is, is there any way of turning normal shop-bought white corn flour into something at least resembling masa harina? I saw a suggestion somewhere that it be put through the blender to make it finer, but that may have been for the purposes of a recipe where the masa was to be used as a thickener. Any other ideas? It doesn't have to be perfect, obviously--even something that just gives the right consistency for the pupusa dough would be an improvement. I just don't want to use wheat flour because it's so boring.

I realise I may be asking the impossible, so I humbly await your pity and derision, and hopefully a suggestion or two too.