Two ingredients, old bread and sugar, and you can have Russian Bread Kvass. . I find home-made sourdough rye and some very dark brown sugar pretty unbeatable taste-wise. And I use the bread cubes again and again, brew after brew, so that they become a bit like kefir grains – a colony of probiotic yeasts and bacteria. . Here are the said bread cubes being filtered out as I pour the fermented liquid into a swing-top bottle for a second fermentation. . My favourite flavouring for this second ferment is raisins and mint. But orange and ginger are good too. . Some more pictures in my story today and the recipe (which includes videos) is the top link in my profile.