Put 1/2 gallon of water into containers that will fit in whatever you are going to attach the immersion cooker to. Put the container in and the immersion cooker. If you are not using jars with a waterproof seal, just put enough water to come to where the yogurt will be. Remove the container the yogurt is going to go in.
The Sous Vide
Put the eight cups of milk into the container you are going to make the yogurt in. Set it in the water with the immersion tool and set it to 185 for 0 minutes. Cover it and let it go. The machine will beep when the milk has reached the correct temperature.
While that is happening, prepare an ice bath. Put ice in a large enough bowl to hold a bowl large enough to hold the yogurt. Add water to make the ice bath.
Carefully remove the container from the water and empty it into the large bowl. Let the milk get to 115 F / 46 C before proceeding, Remove some of the water from the container of water and replace it with cold water until it gets to at least 100 F / 37 C. Set the immersion tool to 109 F/ 43 C.
Use a ladle to take a cup of the warm milk to put it in a small bowl.
Add the half cup of yogurt to the warm milk and whisk it until it is thoroughly mixed in. Pour that mixture back into the warm milk.
Put the yogurt mixture in the container you wish and gently lower it into the preheated water. Keep the yogurt in the water for at least 6 hours, 8 hours preferred. Refrigerate it overnight and be happy the next morning!
Straining
If you want thicker yogurt, you can strain the cooled yogurt with cheesecloth and hang it and catch the whey to give to your pets or use for other foods.
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