Oh no! I'm out of self-raising flour...
This happened to me the other night. I was sure I had some in the cupboard, but when I got home from shopping, nope, not a puff of self-raising to be seen. It was pouring rain, so I wasn't going back out again, so it was either find a solution or can dessert. Thanks to google I now know this:
1 cup of plain flour + 1 tsp of baking powder sifted together = 1 cup of self-raising flour
PS I have no idea what is in baking powder that makes this happen :)