Kombucha is made by adding yeast and a culture of bacteria to a mixture of black or green tea, sugar, and sometimes additional flavorings or fruit juice. The tea and sugar are blended and then turned into kombucha with the help of something called SCOBY (symbiotic culture of bacteria and yeast). This live bacteria sets the stage for a fermentation process, which is what gives kombucha its subtle effervescence and tart-tangy taste.