The two ingredient pizza dough recipe calls for 1 cup of Greek Yogurt and 1-1 1/2 self rising flour. I can't find 'Greek Yogurt' where I live. Can I use 'natural yogurt'? Or whatever.
You can make your own version of Greek yogurt and it will be even better than what you buy in the stores. What you need to do is buy "plain unflavored yogurt", preferably full fat or whole milk. Then get a cheese cloth, and put the yogurt into the cheese cloth that is covering a bowl (please make sure the cheese cloth or a very thin cotton type wash cloth not (like a bath towel) but very smooth like a bed sheet, is secured over a bowl so that the yogurt can drain and the cloth will stay in place. It will take an hour or maybe two or even three, but the water will come out of the yogurt and it will be thicker and richer. I think the water that comes out is called whey. Preferably buy a middle eastern brand of yogurt, or an Armenian or even Russian brand. There is something different in those brands that tastes a little bit better, especially if you get the water out, Mountain High is also good. You can also buy something called "lebni" but that is a different product of yogurt, similar process, but if you try what I say, it will work fine. If you do this with nonfat or lowfat, it is ok also, but we prefer the whole milk style and my friends and family do not like the Greek yogurt at all. Funny, my Greek friends don't care for Greek yogurt either. We find Greek yogurt has more of a cloudy taste rather than a crispier creamier fresher taste and not so heavy and old as Greek yogurt. Good Luck
The point of the yogurt in this recipe is both flavor and for the acid in the yogurt to react with the leavening agents in the self-rising flour (usually baking powder) so that the dough will rise.
Greek-style yogurt is regular yogurt that is strained to remove most of the liquid (yes, it is whey) and you can do this yourself the way user33210 instructs. You want a texture like a very soft cheese. You'll need about 2 c regular yogurt to end up with 1 c of Greek-style strained yogurt.
The flavor of the resulting strained yogurt will depend on the yogurt you start with and how you handle it while straining it.
If you strain it in the refrigerator it will stay unchanged, if you strain it outside the refrigerator it will tend to become more sour as the yogurt bacteria become more active.
Actual Greek yogurt from Greece doesn't taste exactly the same as Greek-style yogurt from the US, but the difference probably doesn't matter for this recipe. Yogurt from different countries use slightly different bacteria cultures and also may tend to be milder or more sour, thicker or thinner styles. The sourness will affect the taste of your resulting dough if it is extremely sour.
I find purchased Greek yogurt and American yogurt are both on the mild side, although I've had homestyle yogurt in Greece that was stronger. If it is an American recipe it is probably expecting a mild-flavored strained yogurt.