Sour Cream Recipe

Prepare equipment

Sterilize or thoroughly wash a small glass jar (8 oz) and a clean spoon. Ensure jar is dry or only slightly damp; a warm jar helps culture start but is not required.

Combine cream and starter

Pour 1 cup heavy cream into the jar. Add 2 tablespoons cultured buttermilk (or 2 tablespoons plain live-culture yogurt). Stir gently with the spoon until evenly mixed. If you prefer a lightly salted sour cream, add 1 teaspoon salt now and stir to combine.

Incubate

Cover the jar with a loose lid, a piece of cheesecloth secured with a rubber band, or the jar lid placed on but not tightened to allow slight airflow. Keep the jar in a warm place (ideal 70–75°F / 21–24°C) away from direct sunlight for 12–24 hours. Check after 12 hours: it should be thickened and tangy. If not tangy/thick enough, leave up to 24 hours, checking every few hours. Warmer temps will shorten time; cooler temps lengthen it.

Chill and finish

Once the mixture is thickened and has a pleasant tang, stir gently, tighten the lid, and refrigerate for at least 4 hours to fully thicken and develop flavor. Chilling also slows culture activity and stabilizes texture.

Storage and use

Use within 7–10 days. Keep refrigerated. If separation occurs, stir gently. If any off smells, mold, or unusual appearance develop, discard. Reserve a tablespoon of your finished sour cream as starter for your next batch (use within 7 days) if you wish to continue making small batches.