I started off with a gallon of 2% milk, picked up from Safeway. Skyr is
traditionally made with skim milk (ok, well, traditionally it's made
with raw milk, but apparently these days it is made with skim), but Siggi's
also makes some "Rjóma-skyr" out of 2% or full-fat milk, and I quite
like it. Anyway, I didn't buy any kind of special milk -- certainly not
organic (or UHT
milk, which is what I'd otherwise buy to keep around the house), since UHT
processing changes the structure of milk, apparently. Just a plain old
cheapo gallon of 2%.
I stuck it in a stockpot, and began the most finicky part of the operation.
Make sure everything is clean, since the goal is to grow bacteria here.
This includes the milk, so the goal is to raise the temperature of the milk
to 190°F for half an hour or so. In practice, this took me about an
hour of screwing around with the stove, and trying to get the heat exactly
right. A Thermapen
lot. Keep stirring, and try not to scorch the milk. I did. I think if I
were going to do this again, I'd consider using the sous-vide circulator for
this step, too. If it develops a skin, take the skin off the top or just
stir it back in.
Eventually, you will have decided that your milk is appropriately
sterilized, and the next goal is to reduce the milk's temperature to the
desired fermentation temperature. I filled the bath for the immersion
circulator with water from the tap as cold as I could get it, and then
dropped the stockpot into the bath (lid on!), and finally plugged the
circulator in and told it to begin circulating without heat. A probe with
the Thermapen told me that I got basically exactly to the 110°F that I
was aiming for.
I separated out a dishful of warm milk, opened a small thing of Siggi's
vanilla, and stirred in about a spoonful into the dish, making sure it was
fully dissolved. Then, I stirred the dish into my stockpot, covered it, and
set the Sansaire
Then, I ate the rest of the thing of Siggi's, and went to bed.