Pour four cups of milk into a quart-sized glass jar.
Sprinkle the entire contents of one Easy Kefir packet into the jar.
Mix well with a spoon and put a secure lid on the jar.
Let this mixture ferment at 72°F to 75°F for 18 to 24 hours. If the temperature is below 72° let it ferment a little longer.
You will know your kefir is ready if the milk has thickened and has a distinctive sour fragrance. The final consistency should be pourable and have a thicker curd.
Place into the refrigerator with a lid. When you put the kefir in your refrigerator the fermentation process continues, but chilling it will slow down the fermentation of the healthy bacteria and beneficial yeast.
To make more kefir from this batch, see notes below — Re-culturing Your Kefir