Place room temperature milk in a mason or glass jar. Add lemon juice or vinegar. Close the lid and give it a good shake.Pro tip - if the milk was in the fridge, make sure to warm it in the microwave for 10 seconds so it's not too cold.
Open the lid again. Now, add the room temperature fresh cream. Close the lid and give it a good shake again. Alternatively, use a whisk to ensure it is well combined. Pro tip - it is important that the cream is room temperature (about 110F) If not warm it in the microwave or in a saucepan on the stovetop. The cooler the cream the longer it will take for the bacteria to ferment.
Cover the jar with a kitchen towel, or use a breathable cheesecloth and rubber band. Pro tip - we want the active culture in the milk to breathe and multiply so we need it to be covered but not sealed.
Let sit in a warm place for a minimum of 12 hours to a maximum of 24 hours. At this time - you should have a thick luscious sour cream. Pro tip - depending on the percentage of fat in the milk and cream some whey would have been separated and resting at the bottom of the jar. This is normal.
Thicker sour cream - If you want thicker sour cream, pour the sour cream in cheesecloth to drain all the excess whey. Pro tip - dry milk powder can also be added to the milk and cream mixture to improve the consistency of sour cream.
Cover the mason or glass jar with its own lid now and store it in the fridge to chill. The sour cream is ready to use. It will stay fresh for up to 2 weeks in the fridge.Pro tip - the sour cream will thicken and mature, making it sourer over time as it cool in the fridge.
Using raw cream and starter culture
Place raw cream in a bowl. Add one sachet of sour cream starter and mix well with a whisk. Let sit for 2 minutes then whisk well againPro tip - it is very important that the sour cream starter is well mixed with the cream so letting it rest and soak then stirring again helps.
Pour the cream into a mason jar and cover with a kitchen cloth or cheesecloth with a rubber band. Leave in a warm, dark place for at least 12 hours undisturbed or until it is set and tastes sour.Pro tip - we want the active culture in the milk to breathe and multiply so cover but do not seal.
Place in the fridge for at least 3 hours before you use it. This sour cream will keep in the fridge for up to 3 weeks.
1 teaspoon of cornstarch helps thicken 1 cup sour cream. Adding too much cornstarch can make it very gummy.
Temperature is important to make things like homemade yogurt from scratch or homemade sour cream. Now I don't want to send you looking for a thermometer but it must be around 110 F which is close to body temperature. If it is heated to a higher temperature let it cool completely before you add the acid or starter.
The second important thing in order to let the sour cream set is warmth and do not disturb. So, you must not peek. I know the first time is very difficult. We are very curious and excited to see if it is working. The active bacteria in there needs to multiply and that happens only when it's warm and untouched. I find the best place to set the sour cream untouched in the oven. Even when switched off the oven is naturally the warmest place in the house. Plus it will stay untouched. If you want to check after 8 hours - slowly open the jar and see. A slight jiggle will tell you if it's set or not. In winter - I put the oven on at 100 F /50 C for just 5 minutes - then I switch the oven off and place the jar in there. Works every single time.
The nutrition information and metric conversion are calculated automatically. I cannot guarantee its accuracy. If this data is important to you please verify with your trusted nutrition calculator. Thank you