What you’ll need to make kefir:
1 gallon jar
plastic mesh strainer
approximately 1/2 gallon (8 cups) raw, whole milk
approximately 2 tbsp kefir grains
No need to measure. Pour the milk into your gallon jar until it is about half full. Use a wooden spoon to incorporate the kefir grains. Cover the jar with a paper towel, securing with a rubber band. You could also use a lid but don’t tighten completely. Leave on the counter for about three days (perhaps two days if it is very hot). Note: most books say 24-48 hours but I find it to be too watery at this point and find three days to be the magic amount of time. When done it should look like the milk is now gelatinous, similar to yogurt. It is normal for it to start to separate, however don’t let this go on too long as the kefir grains will start to eat themselves, versus multiply. Pour the mixture through a mesh strainer into a bowl, using a wooden spoon to gently stir and help the liquid into the bowl. I have been told not use metal utensils at any point as this can disrupt the ph balance of the kefir grains, however other resources don’t mention this. Once only kefir grains are left in the strainer you can either start a new batch or store them in a jar in the fridge for a few weeks, covered with a bit of raw, whole milk*. Kefir should store in the fridge for a few weeks. You can also experiment with leaving it bottled on the counter to get more effervescent.
*somehow I didn’t get the memo and for years have been storing my kefir grains in a jar in the fridge without milk! But I learned recently that you should keep them in milk so they have a little something to nosh on.