Place your active kefir grains in a clean, pint-sized glass jar.
Add 2 cups of whole or goats milk and stir with a wooden or plastic spoon.
Cover your jar with either a lid, or a doubled-piece of cheesecloth secured with a rubber band.
Let the milk ferment on your counter, in a slightly warm spot, for 12-48 hours. The kefir is ready when pockets of whey start to appear, and the milk has thickened considerably.
Set a fine sieve over a small glass bowl or measuring cup. Pour the fermented milk kefir into the strainer and use a plastic or wooden spoon to push the kefir through the strainer, leaving the grains behind.
Retain the grains for your next batch of milk kefir.
Pour the finished milk kefir into a new clean glass jar and top with a plastic lid. You may store the milk kefir in the refrigerator for later use, or you may proceed with a second fermentation.
For a second fermentation, place the covered milk kefir in a warm spot on your counter for another 12-24 hours. Secondary fermentation further reduces the milk sugars, and may help those who are slightly sensitive to dairy or lactose (although not for those who have allergies or intolerances). A secondary fermentation helps mellow the flavor as well.
If you opt for a second fermentation, store your milk kefir in the fridge after the second fermentation.