I have recently discovered from the food-bloggersphere this new idea that is almost hard to believe — that the brine from a can of chickpeas behaves almost exactly like egg whites. It’s known as aquafaba (meaning bean water) and there is a whole website on it (aquafaba.com). It’s a revelation
for people who don’t eat eggs or want to avoid raw eggs (e.g. pregnant women). No one seems sure why it works for things such as pavlova and meringues but there’s lots of research going on at the moment. I did quite a bit of experimenting to get this mousse right. The key part is to add enough liquid to the chocolate while it melts. One drop of water will make the chocolate seize, but strangely enough with more liquid it flows again. Chocolate is actually very dry. If you ignore the fat content, you can think of it as just cocoa powder. A few drops of water makes dry powder go lumpy but more water makes it liquid — the same applies to chocolate. Aquafaba behaves as though it’s wetter than egg white, so some of my attempts at this mousse went grainy before I discovered the trick of adding liquid to the chocolate first to pre-empt the problem. Use the chickpeas from your can to make a batch of hummus.
