Gently heat milk in a saucepan until it reaches 160*. Turn the heat off and stir in citric acid. As you stir, it will begin to separate and curdle, and will take less than 2 minutes or so. (At this point I think this is called cottage cheese.)
Once it's mostly all separated and clumpy, pour the cheese onto a cheesecloth that is draped over a collander which is setting over a bowl. Tie the corners of the cheesecloth up and hang them onto a knob and let the whey continue to drain into the bowl.
After about 45 minutes or so, it will be dry enough to crumble into your recipe, or add sea salt and spices and/or herbs or do whatever you'd like with it. Enjoy!