1 quart milk (mixed from powder)1/2 C buttermilk (mixed from powder)
Combine and let stand for 12-15 hours at about 75 degrees Fahrenheit (either a warm place, or in a thermos or insulated pitcher). When it thickens and sets up to a jelly-like consistency, move it to a cheesecloth-lined colander and allow to drain in a cool place for 4 to 8 hours, stirring once in a while. It will become quite thick, and you can use the whey as well as the sour cream.