I'm not going to bother with the controversy over the health benefits of kombucha. It's a mysterious, ancient elixer fermented with a thick rubbery "mushroom" (the mother), which is actually a symbiotic colony of bacteria and yeast (also called a SCOBY). Nobody has ever found a kombucha SCOBY in the wild, but it entered recorded history around 250 B.C. in China. The main thing is, it's a delicious, non-soda, (mostly) non-alcoholic, tart, fizzy, refreshing beverage.
The common wisdom is that to make your own kombucha, you have to buy a kombucha mother for a lot of money online, or acquire one from your housemate's boyfriend, who got it from a girl on Craigslist in exchange for a ride to Portland. Sadly, the girl on Craigslist may have a subpar kombucha mother. It's hard to tell, but not all kombucha mothers are the same. A neglected kombucha mother, or any of its descendents, will fail to produce delicious, fizzy, happy kombucha -- and it may even breed fruit flies.
Commercial kombucha brewers work with very high-quality kombucha mothers. You can propagate a high-quality kombucha mother of your own with just a bottle of raw kombucha from your favorite kombucha-brand, a little care, some sugar, and good black tea.
Here's why. Every bottle of raw kombucha has very small strands of kombucha mother in it. Your job is to feed those strands until they form a strong kombucha mother. Too much food, and the kombucha won't be strong enough to culture the substrate and it will mold. Too little food, and it won't grow.
Growing the MotherFirst, select an excellent bottle of plain or gingered kombucha. It should have as many yeasty filaments floating in it as possible, and it must be raw. Heat kills kombucha. You can drink some of the kombucha if you like -- just leave all the sediment & stringy bits in the bottle, and at least half a cup of liquid. Next, ready the kombucha food.
In a small saucepan, heat 1 cup water to boiling. Add two tablespoons white sugar, and return the liquid to a boil until the sugar is dissolved. Turn off the heat and add one bag of organic black tea (or a tablespoon of looseleaf) and let the mixture cool at room temperature until it no longer feels the slightest bit warm to the touch. Remove the tea bag or strain the tea. Pour all the contents of the kombucha bottle into the sugar-tea -- the the sediment, the half-cup of kombucha liquid, and the stringy things (these will turn into the kombucha mother!), and put it all in a glass quart or pint jar. Cover the jar with a cloth and a tight rubberband to keep bugs out, and place it in a warm, dark, safe spot. Note that the kombucha liquid is necessary to keep the mixture sufficiently acidic. If the liquid is not acidic, mold will grow.
Keep an eye on the kombucha. In a few days or a week, it should star to grow a thin film over the surface. The film will thicken and become the kombucha mother. If any mold appears, discard everything and start over -- but that shouldn't even be a possibility if you have enough acid in the liquid.
When the film is about an eighth of an inch thick, you'll need to give it another little boost of food. It's not yet strong enough to culture a lot of kombucha for you to drink -- right now it's just growing.
This time, make a quart of tea. Heat four cups water to the boil, add 1/3 cup sugar, and steep with 2 tea bags or 2 tablespoons black tea. When the liquid cools completely, remove the tea leaves, put the baby kombucha and all the liquid and sediment in a large glass jar or bowl with the tea. Cover it tightly and watch it carefully. The kombucha mother should thicken significantly over the space of two weeks. When the mother is between 1/4 and 1/2" thick, you can use it to make yourself a batch of kombucha.
Making KombuchaHeat three quarts water to the boil. Add 1 cup sugar, return to the boil until dissolved, turn off the heat, and add 4 tea bags (or 4 tablespoons looseleaf) black tea. Let cool completely to room temperature. Remove the tea bags or leaves, and put it in a one-gallon glass jar. Pour in a cup or two of finished kombucha liquid from the last batch (to keep everything acidic) and place the kombucha mother on top. It's okay if it sinks. Cover it securely with cloth and a rubberband, and place it in a warm, dark cupboard for a week or ten days. A new kombucha baby will grow on the surface of the liquid. When the kombucha baby is about 1/8" to 1/4" thick, taste the kombucha. If it doesn't taste too sweet, you can harvest the liquid (saving some for the next batch) and repeat the process.
And you can give the baby kombucha to a friend or someone who gives you a ride to Portland.