Start with the basic ingredients for Sour Cream (/how-to-make-sour-cream). Instead of letting it sit until the consistency of jelly, wait a while longer, until it’s even stiffer (like jello). Cut into 1- or 2-inch cubes (depending on how large you want the finished curds to be) and add 2 C water. Heat to 100 F and hold that head for about an hour, stirring occasionally. The whey will come out of the curds and they’ll become more compact. Drain. You can use the whey for cooking, if you like.