Yogurt is a cultured milk product that requires only two ingredients: milk and a starter culture. My favorite commercial brand of yogurt to use as a start is Cascade Fresh plain yogurt. It contains more diverse active cultures than most brands. However, any yogurt that contains "live, active cultures" will do the job. Just check the label. Also, the less additives in the chosen start, the better: flavors, colors, sweeteners, ect.
Begin the yogurt by warming 3 1/2 cups of milk up to a temperature between 105* F and 120* F. This is very warm, but not hot enough to kill the live cultures. Blend in about 4 Tablespoons of fresh yogurt as the starting culture. Blend well to incorporate.
Now the milk just needs to be undisturbed and warm to allow the cultures to grow. Set the warm mixture into a quart jar and cover it with a lid. Then set the jar into a small cooler (one that would hold 2 6-packs of soda pop) and fill the cooler with equally warm water. This is just one method to maintain a steady temperature.
The yogurt is complete and the milk is cultured after about 4-10 hours. It goes faster if the temperature is well-maintained. Otherwise, it takes longer. Carefully check the yogurt with a spoon to see if the mixture has a thick and creamy consistency. It should look something like this.
Simply cool the yogurt in the refrigerator; this will stop the growth of the cultures. The yogurt is now ready to use. But wait! Before using any of the new yogurt, remove about 4 Tablespoons of yogurt and store it in the refrigerator for the next batch. I have been able to keep a good culture going for about 6 months. (Going on vacation wasn't good for it. It is most active when it is maintained and used often.)
Our favorite way to use the yogurt is as a drink. It is delicious mixed with fresh strawberry freezer jam, real fruit juices or fruit nectar. This morning's version was mixed with orange/peach/mango juice. Delicious!
Yogurt's versatility is tasty! It can be used to make a mild cream cheese, sour cream substitute, terrific marinade, delicious frozen yogurt or cucumber sauce for Greek gyros. And, don't give up if you produce an occasional non-yogurt result. These sour-milk products make terrific pancakes and waffles.