Combine in a sterilized jar. Stir and cover with a clean cloth or a clean coffee filter and let sit on counter or somewhere that is approximately 70°F for 12 – 24 hours. Then cover with a lid and refrigerate for another 24 hours.
Notes
Note: do not use ultra pasteurized.
Recipe by Make Mine Lemon at https://www.makeminelemon.com/creme-fraiche/