Kefir, a fermented milk drink rapidly becoming more popular here in the U.S., can be made in two different ways--using commercial freeze-dried cultures or with a SCOBY or SCOBYs, strange, cauliflower-like globs that are often shared between neighbors or passed through generations. These SCOBY globs are also called grains. Here's a recipe for how to use those grains to make this amazing beverage.
Step 1: Start with milk.
Find high-quality milk. It can be cow's milk, goat's milk, pasteurized milk, raw milk. It can be homogenized or cream top. It can even be ultra-pasteurized, shelf-stable milk (think Parmalot). Just make sure it tastes good to you and that it not expired. Bring approximately 1 cup worth of it up to room temperature (roughly 23°C or 73°F). Don't worry about hitting that exact temperature. A ballpark estimate is fine. You can heat the milk on the stove top or you can simply let the milk sit out on the countertop.
Step 2: Add live kefir grains.
Likely, your source for the kefir grains will be a previous batch of kefir. However, if you've never made kefir before, you'll have to source grains either online (like here) or through a community network (such as on Craigslist or through a food coop). Add at least two grains (they'll be about the size of an almond, roughly) to the 1 cup of room temperature milk. You can add more grains than that which will simply shorten the amount of time it takes for your milk to ripen.
Step 3: Cover jar with a lid and wait.
Cover the jar with a lid then again with a towel. The lid can be tightened down (which will create a little bit of effervescence) or it can be loosely screwed on. The purpose of the towel is to block out the sunlight (UV light will alter the nature of the grains). Alternatively, you could put the cup of ripening milk inside a dark cupboard. Hold the milk at room temperature for anywhere from 4 hours to several days. For your first run, try holding the milk for one day (24 hours).
Step 4: Notice the milk changing.
There are several ways to know if your milk is successfully ripening. First, when you open the lid, you should notice a sour, lactic smell. Next, you should notice that the milk changed from liquid to solid or semi-solid. Depending on the nature of your grains and how much you tightened the lid, you may see bubbles--an indication that some of the milk sugar (lactose) was fermented by yeasts.
Step 5: Strain the ripened milk.
When enough time has passed, strain the milk. This is as simple as pouring the contents of the jar into a colander or sieve. Hold the sieve over a bowl to catch the ripened milk. Left behind will be your kefir grains. With time, the grains will start to multiple so you'll have more and more.
Step 6: Collect finished kefir.
The liquid you strain away is the finished kefir. It is ready to enjoy right away, if you'd like.
Step 7: Set aside the grains.
In the sieve will be left with a bunch of milky grains. Save these because you're going to use them to start the cycle again. Hydrated grains, such as you now have, are alive and need food (new milk). If they're left out of milk and at room temperature, they will start to evolve into grains that don't perform the way you want them too. Best is to move them quickly onto the next batch.
Step 8: Sweeten the kefir as desired.
Only when the milk has finished ripening should you stir in flavorings or sweeteners. Add honey, brown sugar, agave syrup, jam, dried fruit or fresh fruit. If you want texture in your final drink, just stir these additions in and drink up. If you want a smooth, texture, put everything in the blender and give it a whirl. Sweetened kefir has a very short shelf life (maybe a day) so don't plan on making a large batch of honey kefir to enjoy throughout the week. Sweetened (or don't) and enjoy!
Step 9: Hold grains in fridge, if needed.
If you need to go on vacation or somehow can't keep up with the amount of kefir you're producing, instead of ripening a fresh cup of milk with grains on the counter top, you can move it right to the fridge. There, the grains will keep for several weeks up to several months. It's a good idea to not try and hold the grains in the fridge for too long or they will die. The formation of a layer of yellow whey at the top of the cup is normal.
Step 10: Enjoy!
Kefir is an ancient beverage and it's incredible healthy! Those kefir grains are a symbiotic community of yeast and bacteria (known as a SCOBY). The SCOBY breaks down the fresh milk--ferments it--into something that's easier for our gut to digest than fresh milk. Adult humans have been drinking kefir-like beverages for far longer than they have been drinking fresh milk.