Blackberry Mint Kombucha

For the First Fermentation: In a large 4-quart or larger pot, combine 4 cups (960ml) water with the sugar and bring to a boil over high heat, stirring occasionally to help fully dissolve sugar. Off heat, stir in tea leaves and let steep until tea registers roughly 150°F (65°C) on an instant-read thermometer, about 15 minutes. Stir in remaining 8 cups (1920ml) water and let cool until tea registers 85 to 90°F (30 to 32°C). Serious Eats / Tim Chin Set a fine-mesh strainer over a one-gallon glass jar that has been run through a dishwasher cycle or sanitized with a product like Star San. Strain tea through it; discard tea leaves. Stir in kombucha starter until well distributed. Gently place SCOBY on top (you should have at least 2 inches of headspace in the jar after adding the SCOBY). The SCOBY may float or sink to bottom of jar; either is normal. Serious Eats / Tim Chin Cover jar with a double layer of coffee filters and secure with a rubber band. Store in a dark area between 70 and 80°F (21 to 27°C) and let ferment until kombucha tastes sour and small bubbles rise to surface, and a new layer of SCOBY has formed at surface, about 7 days and up to 4 weeks (pH should register roughly 2.9 on a pH meter or pH strips). Serious Eats / Tim Chin For the Secondary Fermentation: Set a fine mesh strainer over a medium bowl. Line strainer with 3 layers of cheesecloth, leaving 6 inches overhang on all sides. In a food processor, process blackberries, mint, and sugar, pausing once halfway through to scrape down sides, until mixture is pureed, about 1 minute. Scrape blackberry puree into strainer and allow juice to drain through into bowl. Gather overhanging cheesecloth, twist to close, then squeeze puree to release as much juice as possible; you should have about 1 1/2 cups (355ml) juice once done. Serious Eats / Tim Chin Thoroughly wash and dry five 16-ounce (1-pint) twist-cap or flip-top glass bottles. Using clean hands, remove SCOBY from kombucha and place on plate. Then, using a funnel, fill each bottle with 1/4 cup (60ml) blackberry juice. Stir kombucha with a wooden spoon, making sure sediment is evenly dispersed, then fill each bottle with kombucha, making sure to leave 1 to 1 1/2 inches of headspace in each bottle (you should have about 2 cups of extra kombucha that won't fit in the 5 bottles; this kombucha can be used as starter for your next batch). Seal bottles and store in a dark area between 70 and 80°F (21-27°C) until beverage reaches desired level of carbonation, 3 days to 2 weeks. Check one bottle periodically to monitor carbonation: it is ready when you see small bubbles rising fairly rapidly to the top, even when capped; if using twist caps, the cap will pop up slightly when a good level of carbonation is reaches; if using flip-top bottles, you may need to open one bottle to check the carbonation, resealing if there isn't enough fizz. When kombucha has reached desired level of carbonation, move bottles to refrigerator and store for up to 8 weeks. Serious Eats / Tim Chin To Continue Brewing Future Batches of Kombucha: Repeat Steps 1 to 5 using the leftover kombucha as starter along with reserved SCOBY and new batches of the blackberry-mint puree.