Yeast Starter
Beer
Boil a pint (1/2 quart) or 550 ml of water and stir in 1/2 cup of DME. This will produce a starter of about 1.040 OG.

Boil this for 10 minutes, adding a little bit of hops if you want to. Put the lid on the pan for the last couple minutes, turn off the stove and let it sit while you prepare for the next step.

Adding a quarter teaspoon of yeast nutrient (vitamins, biotin, and dead yeast cells) to the starter wort is always advisable to ensure good growth. Carefull it can foam up quite a bit when boiled or added.
 
Yeast Starter