Leave milk out of the fridge for approximately an hour so that it is room temperature.
Add milk to the sterilised jar. Add kefir grains. Cover with cheesecloth, mesh or coffee filter.
Gently stir using a wooden spoon (do not use metal implement).
Place the jar in a spot that has consistent room temperature or in the pantry but not in direct sunlight. Ideally somewhere with a constant temperature between 18-25°C.
Leave to ferment for 24 hours or until the product thickens or sours to your liking.
Once the Kefir shows signs of separation and/or thickening, the kefir is ready. You may notice small pockets of whey. Leaving Kefir to ferment for too long after this can make it sour, which is OK, however, no longer than 48 hours is recommended.
Strain through a non-metallic sieve stirring with a wooden or plastic spoon. However, be careful not to squash the grains. Place the grains into another clean dry sterilised glass jar with milk to start your next batch of kefir.
At this stage, you can do a second ferment to increase nutrients including vitamin Bs and probiotics. Simply leave the kefir at room temperature for another 8-12 hours.
You can drink your strained kefir straight away or keep it sealed in the fridge. It will last for 2-3 weeks in the fridge.