Tired Of Baking? Turn Your Sourdough Starter Into Kvass

As someone who has kept a sourdough starter since the Before Times, I am constantly looking for new ways to use the little jar of wild yeast goo that lives on my kitchen counter. As is the case for most sourdough parents, pancakes and waffles were my gateway into alternative sourdough uses, followed by crackers, grissini, and all manner of quick breads. As the years went by, I started sneaking starter into pie crusts, cookies, brownies, and cakes.

During the early stages of the pandemic, my enthusiasm for sourdough baking continued to flourish. I started maintaining multiple starters—white flour, half white/half whole wheat, rye, 50% hydration—and baking multiple loaves of bread every week, which left me with an abundance of both bread and discard. I thickened soups with stale bread and topped macaroni and cheese with homemade bread crumbs, but I knew I could do more.

By the middle of this summer, I was desperate for something new to do with my starter, ideally something that didn't require me to turn on the oven. I'd experimented with fermented sodas in the past using ginger bugs and sauerkraut liquid, but it had never occurred to me to try using my sourdough starter to make a beverage. That's when I remembered kvass.

Kvass is a wildly popular drink in much of Eastern Europe, with origins dating back to the Middle Ages—the first mention of kvass in print is found in the Russian Primary Chronicle, published around 1113 AD. Peasants, monks, and other citizens of ancient Rus' drank more kvass than water since the fermentation process made it safer. It was also used as a base ingredient for several economical chilled soups, such as okroshka and tyurya, both of which combine chopped vegetables and sometimes smoked meats with kvass for a savory take on something like milk and cereal.

The drink is still popular in modern-day Russia, where there's a huge market for commercial kvass. Drinking kvass is now also considered to be somewhat of a patriotic act. One of the country's most popular brands, Nikola, also sounds like "not cola" in Russian—and that's not an accident. In the summertime, you can still find small-scale brewers selling their own versions out of huge tanks and barrels on the street.

Kvass has been slow to catch on in the U.S., and it's still hard to find in stores that don't specialize in Slavic ingredients. It's fairly similar to kombucha but with a funkier flavor that bears some similarity to the dank brews of modern craft beer. It's also a great entry to homebrewing, since you don't need to purchase any special equipment, yeasts, or starter cultures to make it.

I tried kvass for the first time last summer, after a trip to the epic Russian grocery stores in Brighton Beach, Brooklyn. It came in a two-liter soda bottle with a monk and the words "Kvas Monastyrskiy" on the label. From the first sip of the nearly black, lightly carbonated liquid, I was hooked on the distinctive sweet-and-sour flavor that paired perfectly with my haul of pickled squash and smoked fish. I immediately dove into researching the history and brewing process, but I soon got distracted by things like leaving my apartment to go to work, a common occurrence back in 2019. This summer, there was nothing stopping me from tackling a batch of my own bread soda.

At its simplest, kvass is just fermented bread water, so all you really need to make it is bread, sugar, water, sourdough starter, and an empty plastic soda bottle. A nut milk bag or cheesecloth will help you filter out solids, and a funnel will make things less messy. Most recipes call for adding a handful of raisins to help kick-start fermentation.

You can use any bread you have on hand for this recipe. When I'm baking a lot, I like to save the ends of my homemade loaves until I have enough to brew a batch. It's also a good way to use stale bread. Every once in a while, I'll get a two-pound loaf of dark Lithuanian rye from my local Russian bodega and use half for sandwiches and half to brew a more authentic-tasting kvass. The flavor of your final product will vary depending on what kind of bread you use as the base. My favorite batch came from the stale ends of homemade multigrain sourdough, which tasted almost like a Hefeweizen at its peak. Every batch of kvass you brew will be a little different, depending on the bread you use, how dark you toast it, the temperature of your kitchen, and so on. It's one of the things I love most about making kvass at home, because it gives me endless opportunities to taste something new.

Carina Finn

Makes around 2 liters

Brewing your own kvass using sourdough starter and leftover bread is an underrated way to get creative with your starter, especially during the summer months. While the process requires very little hands-on time, it is a bit lengthy, so make sure you consider the whole timeline before you get started. Any bread will work for this recipe, but the bread you use will impact the flavor profile and color of the beverage. In general, pumpernickel or rye will give you a darker, more traditional kvass, whereas breads made from other grains will yield a lighter, more nuanced end product. Kvass is technically ready to drink three days after bottling, but I've found that it gets significantly better after around a week of aging. The fermentation process will continue in the bottle, and as the kvass ferments, more sugar is eaten up in the process, which yields a less sweet, more complex flavor.

• 1 lb. bread, cut into slices
• 2.5 liters water
• 1 cup sugar
• 1 Tbsp. active sourdough starter
• ¼ cup raisins, currants, or other dried fruit

Lay sliced bread on a large sheet pan and toast under the broiler on high. You're trying to caramelize the sugars in the bread, so go darker than you would if you were making toast to eat, but don't burn it. Flip the slices halfway through so that both sides are fully toasted.

While your bread is toasting, bring 2.5 liters of water to a boil in a large pot, then remove from heat. Submerge toasted bread in the pot of hot water, cover loosely, and let sit for 10-12 hours, or overnight. Feed your sourdough starter now to ensure that it's active and ready to go for the next step.

At this point, you should have a liquid that is essentially bread tea. Strain out the liquid into a large bowl or pot. I like to use a nut milk bag for this step, because it allows you to squeeze out every drop of liquid from the soaked bread. You can also use a fine mesh strainer lined with cheesecloth or paper towels. If you don't have any of these things, just carefully tip the liquid out of the pot, pressing the liquid from the bread with the back of a large serving spoon.

Whisk in sugar and active starter to your strained liquid, then stir in a handful of raisins. You can also adjust the flavor of your kvass by adding herbs or other fresh or dried fruits during this step. Cover loosely and let the mixture stand at room temperature for 8-10 hours. When it's ready to bottle, the mixture will be foamy and have a slightly sour smell.

Strain the liquid again before pouring into empty plastic soda bottles. Be sure to leave about one-third of the bottle empty to maximize carbonation. If you leave less head space, your kvass will be more lightly carbonated. Kvass can explode if you leave sealed glass bottles unattended in a warm room, which is why I always use plastic for this project.

Tighten the caps and place your bottles in the fridge. Check them on a daily basis by lightly squeezing the bottle—if it feels very firm, loosen the cap slightly to release some of the pressure, then tighten it again and return the bottle to the fridge.

You can start drinking your kvass after three days, but it tastes best after aging for about a week. There will be some sediment at the bottom of your bottle, which is just built-up yeast from the fermentation process. I like to shake the bottle gently to mix it in, but some kvass-makers prefer to let it settle and drink only the milder liquid on top.

The beverage will become less sweet and slightly more alcoholic the longer it sits and the sugars convert into alcohol, but the maximum alcohol content will likely be around 2%. Kvass will keep well in the fridge for about a month, but as with all home fermentation, when in doubt, throw it out, especially if you see or suspect any mold in your brew.