​​​​​Homemade Sour Cream Recipe | CDKitchen.com

Combine cream with buttermilk in hot, clean glass jar with a lid. (Canning jar that has been heating in boiling water, for instance.) Cover tightly and shake gently to thoroughly mix. Let stand in a warm place - like where you put bread to rise) till thickened (24-48 hours). Store, covered in refrigerator. Stir before serving. Use within three weeks.