Sour Cream Recipe

Sterilize and measure

Sterilize a glass jar (about 2-cup / 500 ml capacity) and a clean spoon by rinsing them in hot water. Measure out the heavy cream and whole milk and set near your workspace.

Warm mixture (optional)

Combine the heavy cream and whole milk in a bowl or saucepan. Warm gently to 20–25°C (68–77°F) if your kitchen is cold to help cultures activate. Do not heat above 40°C (104°F). If your kitchen is room temperature (20–24°C / 68–75°F), you can skip warming.

Add the starter: Stir 2 tablespoons of live-culture buttermilk or plain yogurt into the cream/milk mixture until fully incorporated. The starter provides the lactic acid bacteria that will thicken and sour the cream.

Transfer to jar: Pour the inoculated cream mixture into the sterilized jar, leaving about 1/2 inch (1 cm) headspace. Cover the jar with a loose lid or a breathable cloth secured with a rubber band to allow slight airflow while keeping dust out.

Incubate at room temperature: Place the jar somewhere with a stable warm-ish temperature (ideally 20–25°C / 68–77°F) out of direct sunlight. Let it sit undisturbed for 24–48 hours. Check at 24 hours: it should be noticeably thicker and tangy; if not tangy/thick enough, let it continue up to 48 hours. Warmer rooms speed fermentation; cooler rooms slow it.

Check texture and taste: After 24–48 hours, gently stir or tilt the jar to assess thickness and taste a small amount. The longer it ferments (within that range), the tangier it becomes. If it’s too thin but tangy, refrigerate to chill and firm up; if not tangy enough, allow more time but check frequently.

Refrigerate to stop fermentation: Once the sour cream has reached your desired tang and thickness, secure the lid and refrigerate for at least 4 hours (preferably overnight). Cooling slows the cultures and thickens the texture.

Season and adjust: Before using, taste and add up to 1 teaspoon salt to taste and, if desired, up to 1 teaspoon lemon juice for extra tang. Stir gently to combine. Do not add large amounts of acid before fermentation — add after chilling if needed.

Storage: Homemade sour cream keeps in the refrigerator for 7–10 days. Use a clean spoon each time to avoid introducing unwanted bacteria. Reserve a tablespoon of finished sour cream as a starter for your next batch (use within a week and keep refrigerated).