Simple Kvas Recipe
* 1/2 kg rye bread
* water to 1 gallon
* bread or brewer’s yeast
* 1 small cup sugar
* 1 fistful raisins or other fruit (anything can be used to flavour, but raisins are traditional apparently)
First let the bread go at least a little stale. Then toast it, and toast it well. A little bit of burning isn’t a problem. If you feel like it you can make neat little croutons, but that’s a preference rather than being important in its own right. While that’s happening have a gallon of water on the boil, and once boiling stir the bread and raisins into it. Leave the mixture of bread and water covered overnight to soak (at least eight hours, but longer won’t hurt the resulting flavour at all). Strain the mixture, adding the sugar and yeast and bottle as you would any other soda (i.e. plastic bottles unless you’re confident enough in your timing to want to risk glass, in which case fill one plastic bottle to test fermentation progress).
Once that’s done you just leave the bottles until they’re hard, and chuck ’em in the fridge. Easy.
If you feel like experimenting then you can also add mint, strawberries, slices of apple, raisins or just about anything else you feel like.