Think of quark as kind of a sour cream meets yogurt. It's easy to make, and as a kid I remember my mom having the perfect recipe. Recently, when I was given some raw milk from local dairy Natural Springs, I knew it was time to give her a call and have her walk me through her methods.
Here are Mom’s directions:
Bring 8 cups of milk to a simmer over medium heat in a heavy bottomed saucepot. Then, remove from heat and let come to room temperature. Whisk in 2 cups of buttermilk (or make your own buttermilk by mixing 2 cups milk with 3 ½ teaspoons acid, typically lemon juice or vinegar).
Transfer the mixture to a glass or plastic container and leave the mixture at room temperature for a day or so until curds form and the mixture thickens. The mixture will become the consistency of yogurt.
Transfer the thickened mixture to a coffee-filter or cheesecloth lined strainer set over a bowl. Refrigerate overnight allowing the curds to strain, removing the clear whey.
In the morning, you've got cheese. You’ll notice your quark can be best described as the kissing cousin of sour cream and soft ricotta cheese. Keep it refrigerated and stored in a covered container, and use as desired!