International Beverage recipe from the Wikibooks Cookbook.
1 gallon homogenized whole milk 1 cup unflavored (plain) yogurt 1 quart half and half cream (optional) 1 teaspoon citric acid (optional) 1 teaspoon sugar (optional)
Add the milk to a large pot. Boil until it starts to foam. Turn off the heat and wait for the milk to cool to room temperature. Stir in the yogurt and half and half. To make your leben more sour, boil the mixture and add the citric acid along with it until it starts to foam. To make your leben more sweet, boil the mixture and add the sugar along with it until it starts to foam. It is not recommended to add the sugar and citric acid together in your leben. This will worsen its taste. Stir well, cover with a towel, and let rest overnight at room temperature. Uncover and stir, then enjoy. To preserve your leben, cool it as a regular dairy product.