This post is part of series on different ways to use, transform and preserve fresh milk. Main article here.
In this recipe, you’ll use finished kefir to culture heavy cream. If you haven’t made kefir at home yet, store bought will work here. Make sure to use a whole milk and unflavored variety.
There are specific heirloom sour cream cultures out there, but I choose to make sour cream this way for a couple reasons. First, milk is more readily available to me than cream. Second, I already maintain kefir grains. I can make a batch of sour cream every now and then when I have time to shop at my local food co-op for cream. Making a fermentation and food preparation routine that is in tune with locally available resources allows me to generate a variety of finished products without having to maintain cultures that require more difficult to obtain ingredients.
The basic ratio is 1:7 kefir to heavy cream. I’ve made as little as a pint and as much as a half gallon. Fermentation time will vary depending on your kitchen temperature. My kitchen runs quite cold in the winter and it’s taken as long as 5 days to finish a batch of sour cream. In the summer, as short as 24 hrs.
3.5 cups/28 oz heavy cream
1/2 cup/4 oz kefir
Combine heavy cream and kefir into a clean, quart size mason jar. Cap tightly and shake well.
Let the cream ferment at room temperature for 1-5 days. In a warmer kitchen (above 75F) it will culture faster, slower in a cold kitchen.
Give it a shake once a day. Start checking for changes in texture and flavor every 24 hrs.
You are looking for thickness similar to Greek yogurt. The flavor should be mildly tangy. I like to poke a chopstick into the jar to check the texture and give it a taste.
When it’s about as thick as Greek yogurt, it’s done. Refrigerate.
Stays good for at least a month in the fridge.