Homemade yogurt is a wonder: Whole milk transformed into silky, beautiful creaminess by the magical alchemy of heat, time and the addition of a bit of active cultures (a quarter cup of yogurt with live cultures does nicely). Really, once you get the hang of it, it's dead simple. The trick is not to heat the milk too high—you don't want to kill the bacteria in the starter. The other requirement is finding a warm place to rest the yogurt. It needs to reside in an environment around 110°. Examples that work: Nestling the yogurt in a heating pad, placing it in a dehydrator or leaving it in an oven with a pilot light and light on. Whatever you rig up, just make sure to strain the yogurt through cheesecloth as it will further thicken and produce a creamier product.
Recipe from the Tasting Table Test Kitchen
Yield: About 1 quart
Prep Time: 10 minutes, plus resting time
Cook Time: 10 minutes
Total Time: 20 minutes, plus resting time
4 cups whole milk
1. Pour the milk in a medium saucepan over medium heat and bring to a gentle simmer, stirring occasionally and scraping bottom of pan with a rubber spatula to prevent any scorching until the milk reaches 180°, about 10 minutes. Remove the milk from heat and transfer to a non-reactive bowl. Allow to sit until an instant-read thermometer reads 110° degrees. You can speed up the process by placing the bowl of milk in an ice bath, stirring constantly until the temperature is right.
2. Stir in the starter yogurt into the milk immediately, working gently. Pour the milk into a sterilized glass jars and cover.
3. Place the jars in a warm place where the temperature remains 110°, making sure not to disturb the jars for at least 8 hours or up to 24 hours. The longer it sits the tangier the yogurt will become.
4. Once the yogurt has thickened, place yogurt in a large fine-sieve lined with cheesecloth over a large bowl. Cover and chill in refrigerator for at least and hour before serving.