Kvass

Ingredients

• 100 g raisins
• 100 g sugar
• 3 slices black bread
• 1-2 lemons
• 1 pkg (7 g) active dry yeast
• 1 L water
• handful (optional) coffee beans
• to taste (optional) non-citrus fruits

Method

Toast the black bread in a dry oven at 180°C until it's charred black on the outside — this caramelisation develops the dark, slightly bitter notes that define kvass. The crust should be brittle and release a toasted grain smell. This takes about 15 minutes, depending on bread thickness.

Boil 1 L of water and pour it directly over the toasted bread, raisins, lemon slices, and coffee beans (if using). The heat opens the cell structure of the bread and extracts the roasted compounds into the liquid. Leave this to cool completely to room temperature — roughly two hours — before filtering. The cooling matters because yeast-fermentation won't start reliably above 30°C, and you risk killing the culture if you pitch yeast into warm liquid. Strain through a fine sieve into a sterilised container.

Dissolve the sugar into the still-warm infusion, then add the yeast once the mixture drops below 25°C. Stir thoroughly — this distributes the yeast cells and ensures even fermentation. The sugar feeds the yeast; the acid from lemon and compounds from the bread create an environment where beneficial fermentation dominates over spoilage. Add the remaining raisins and any other dried or stone fruits now. These provide secondary flavour and additional fermentable sugars that extend the complexity as the yeast works. Transfer to a sterilised mason jar and seal loosely — a light cloth cover works better than an airtight lid because fermented-foods need to off-gas carbon dioxide without building pressure.

Keep the jar at 26–28°C for seven days. You'll see vigorous bubbling for the first two to three days, then it will slow. By day seven, bubbling should have nearly stopped — that's your signal the yeast has consumed most available sugars and the fermentation is finishing. Strain out all solids.

Squeeze fresh lemon juice into the finished kvass just before drinking — the acid brightens the flavour and stabilises the colour. Chill and serve immediately, or refrigerate for several days. Kvass doesn't age like wine; it's best consumed fresh.