Wash the equipment, including wooden spoons, a pot, and jars, in hot soapy water. Rinse well.
Place the jars on the middle shelf in the oven (no plastic parts) and sterilize them for 10 minutes at 320ºF/160ºC.
Prepare the milk
Add the milk to your saucepan or pot. Heat it over medium heat, stirring frequently, until it reaches 175-185ºF/80-85ºC. Remove the pot from the heat.
Cool the milk to 108-112ºF/42-44ºC. Either set the pot aside and let it cool naturally (20+ minutes) or place it in an iced bath to speed up the process (1-2 minutes) and stir continuously for uniform cooling.
Combine the plain yogurt (or starter) with ½ cup of the warmed milk and stir well. Add the mixture to the pot and stir gently.
Fill the jars and incubate
Pour the milk into the sterilized jars. If needed, clean the rims. Close the lids.
The jars need to be placed in a warm environment at a constant temperature. You can wrap them in a blanket and put them in the oven (with the heat off!).
Incubate the yogurt for 7-9 hours until it has thickened and becomes jiggly. The longer you leave the yogurt to ferment, the tangier it will taste.
Refrigerate and enjoy
Once the incubation period is over, transfer the jars to the fridge. For thicker results, allow the yogurt to set for a couple of hours before enjoying it.
Enjoy your homemade yogurt, and make sure to reserve a few tablespoons to use as a starter for your next batch.
Video
Notes
To store: The yogurt will last 1-2 weeks in the fridge. For maximum shelf life, always use clean utensils in the container. Even better, store it in several smaller airtight jars.To freeze: You can also freeze the yogurt for up to two months. Divide the homemade yogurt into portions—either in a freezer-safe bag or container or in smaller ice cube trays—and freeze. Then, leave it in the fridge overnight to thaw before using.Check the blog post for how to use homemade yogurt.