- 1 tablespoon home-cultured buttermilk (see my recipe in a separate post)
- 1 cup heavy cream
Pour the buttermilk into a heat-resistant glass jar. Add the cream.
Place the lid on the jar. Place the jar into a bowl or pot of warm tap water for several minutes, until the jar of buttermilk-to-be seems to be around room temperature. Remove the jar from the water and leave it on your kitchen counter. Every now and again, pick it up and give it a good shake-a-shake. The frequency of shaking is unimportant. It's fine to leave this unattended for many hours, like during sleep or if you go off to work.
After about 6–12 hours, you'll have sour cream. Refrigerate. This gets thicker and tastier over the course of the next couple of days.
After about a week, the flavor will begin to deteriorate. So don't let your lovely sour cream go to waste! Use this everywhere you might use commercial sour cream, or yogurt, whipped cream, mayonnaise, cottage cheese or (gag) Cool-Whip.
You can use store-bought buttermilk, also. It won't taste as good. But it's still a fun experiment!
As with all food, the better your ingredients, the better your results. Look for the best, freshest cream with the least amount of additive gunk. Organic and local if at all possible.
I just got this hint from a low-carb forum where I like to hang out: Organic Valley uses the seaweed-derived thickener carageenan in their ultra-pasteurized heavy cream, but not in their (non-ultra-)pasteurized heavy cream. I have nothing against carageenan itself. However, they make their darn cream too thick! I look forward to trying out their pasteurized cream (if I can find it) and seeing if that really is better. Pasteurized is better for you than ultra-p (more vitality remains), anyway.