TO MAKE YOGURT:
Pour desired quantity of MILK into a clean, wide-mouth glass
jar(s). Any % fat milk can be used; but lower % s will be
more tart and less creamy. I use 2 % or 4 %.
Heat to about 180 degrees F.; I do this in the microwave. (You
can use full power at first, but as the milk warms up, use a lower
setting, to keep the milk from boiling over all over the
Let the milk cool, still in the microwave, to about 125
degrees. Then cover jar top with a clean sandwich bag, and put it
in a place it can stay warm.  I use a mini-cooler. Let milk
continue to cool, to 90 to 100 degrees. (Temperatures over 135
will kill the yogurt culture. Temperatures over 100 will make the
culture set too quickly, resulting in a curdled sort of texture.
Moving the jar to your cooler when the milk is 125 degrees warms up the
cooler just enough.)
Stir YOGURT (see note below) into the milk, about 1 Tbsp. yogurt per
cup of milk. Re-cover jar top. Place jar(s) back in the
mini-cooler. Leave undisturbed for about 8 hours. Jiggling
can disturb the culture and keep it from "gelling." Milk should
become the consistency of a light custard. After chilling in the
refrigerator, it will become a little firmer. You have
NOTE: Yogurt for starter can come from your last batch, or
from some purchased at the store. if purchased, it has to have
active yogurt culture as an ingredient. My favorite for a creamy
texture is Brown Cow.
TO MAKE YOGURT CHEESE/GREEK YOGURT:
Strain yogurt (either homemade, or commercial without added gelling
agents), using a colander lined with coffee filters/s or food-safe
paper towels, over a bowl, in the refrigerator, for 12 to 24
hours. Discard the clear whey that drains off. (some say it
makes a refreshing drink, but I'm not buying it.) The resulting
yogurt cheese is a wonderful substitute for sour cream to make dip, top
potatoes, sweeten for a fresh fruit sauce, etc.
But... beware that it will separate/curdle if cooked! If you
want to try using it in place of sour cream in a cooked sauce, try
adding 1-2 Tbsp. of cornstarch per cup of yogurt cheese, thoroughly
mixed into the yogurt cheese.