I watched a video on the 'Net about making crème fraîche. You may have seen that one or a similar one yourself. Looks easy enough.
Well, I needed some crème fraîche so went shopping. I can get eight ounces for six bucks, or maybe less, but really, does it matter? No, because it's supposed to be easy to make. So I bought a pint of organic heavy cream, pasteurized but not ultra-pasteurized, some buttermilk, and a half-liter jar. Total cost, $6.93. Could have spent less on the cream, but I was at Whole Foods (my favorite grocer) and that's what it cost.
Cleaned the jar, brought some water to a boil and sterilized it, then put the cream on the heat until just tepid. Poured it into the jar, added three tablespoons of buttermilk and stirred. Sealed the jar, put a note on it letting people know it's supposed to be out on the counter, and let it sit out. It's supposed to be at warm room temperature for 24 hours.
After 12 hours or so, I remembered I'm supposed to stir now and then, so I did. There's a very faint sour odor and taste--a really pleasant sour, not the throw-it-away sort of sour. Over the next 12 hours it has thickened slightly and developed a very pleasantly tangy sourness. It goes into the refrigerator at this point.
After being in the refrigerator 24 hours it should have thickened. It thickened a little, but isn't as thick as I think it should be. But it tastes fine. It whipped nicely, and I added some chives and fleur de sel to it to use as a topping on a fritatta.
Making crème fraîche is extremely simple. I could buy it, paying between forty and eighty cents per ounce, but now that I've tried making it--at twenty-seven cents per ounce--I'll never buy it again.
I'll experiment a bit more to see if I can get a thicker crème. I'll update this post with results when I have some.
Update: "Looks easy enough," he said. Not so fast there, it isn't quite as simple as it looks.
I've checked half a dozen videos and about twenty recipes, on- and off-line. There is agreement that you need cream, that you heat the cream, that you add buttermilk, that you let it ferment, and that you refrigerate it.
The recipes all specified varying amounts of cream, but agreed that it should be 30% butterfat and pasteurized but not ultra-pasteurized. Then you heat the cream to between 85° and 105° Fahrenheit, or to body temperature, or to tepid. Then you add between one teaspoon and one and one-half tablespoons of buttermilk per cup of cream. The mixture sits out 8+ hours, or overnight, or 24 hours or 24-36 hours until thickened, and then is refrigerated 6 hours or overnight or 24 hours.
I used a pint (2 cups, 16 ounces) of heavy cream, heated to 105° Fahrenheit. I put three tablespoons of buttermilk into my half-liter jar and added the heated cream to fill, leaving about ¼ cup in the pan. After 24 hours, I was dissatisfied with the thickness so let it sit out another 12 hours. The flavor richened over that additional time, but did not get more sour. It went into the refrigerator, and after about 6 hours I could use it if I want, but it still isn't as thick as I'd like. I'm going to let it "age" a bit and see what happens.