OR 1/8th teaspoon mesophilic starter culture (like this)
OR 1 cup sour cream with live, active cultures*
*If using 1 cup of sour cream as your starter, reduce the amount of heavy cream to 3 cups.
Instructions
Gently heat the cream to 86 degrees Farenheit. Stir the starter culture into the warm cream.
Cover it loosely with a towel and rubber band, and allow it to sit at room temperature for 12-24 hours, or until it is thickened and tangy.
If you like, you can now turn your sour cream into cultured butter, or just drizzle it (or plop it–depending on the consistency) on your favorite dishes.