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I finally figured out how to make yogurt that’s as sour as the yogurt I had in Syria (at least this is closest I’ve ever gotten)! If you’re always disappointed by the lack of tang in commercial yogurt, follow along! I’ll post what I’ve learned along the way... 
I learned how to prepare yogurt from Leila Dom in Aleppo in 2009: https://bit.ly/3sUuCWb . She taught me the classic Teta technique of wrapping yogurt in towels to keep the milk warm during the incubation period.
By preparing yogurt in individual jars instead of a large pot, I learned how to avoid the watery pools of whey (as long as you go through an entire jar of yogurt in one sitting, which is not a problem for me)
A couple years ago, I began to wonder how people prepared yogurt before fancy yogurt makers, stainless steel pots, and glass jars. This question about yogurt led me to a story about a material: clay. For thousands of years, people prepared yogurt in clay vessels. But why?
It turns out clay has two fantastic properties! 1) Clay has relatively low thermal conductivity. This means it does not transfer heat as quickly as other materials like metal or glass, for example.
This property is ideal for making yogurt because it keeps milk warm during the incubation period. I still wrap the clay pot in towels because I’m a Teta (and every bit of warmth helps). Aside: This property is also why people stored cool water in clay jugs before refrigeration.
2) Clay is porous! Remember the pools of whey? The walls of the clay pot absorb much of this whey which results in a wonderfully thick and creamy yogurt— not quite labneh (strained yogurt), but thicker than commercial yogurt.
After learning all this, I worked with a local artist and brilliant ceramicist out of Baltimore, Tamer Zaki, who made the most beautiful clay pot for me.
If you’d like a clay pot, I recommend reaching out to your local potter’s guild if you have one (to support local artists). You could also find high quality clay pots online from Miriam’s Earthen Cookware: http://bit.ly/3of3fmm
There are many factors that can contribute to the sour flavor I’ve been searching for: incubation period, culture/yogurt starter, type of milk, incubation temp. I’ve experimented with most of these with varying degrees of success. I’m here to report what worked though...
Before the holidays I turned all the milk in my fridge into yogurt the way I normally do. I did an 18-hour incubation period, but this time I left the yogurt in the fridge for six weeks while I was away! When I came back, the yogurt tasted a bit intense, but not bad. I ate it.
Then I made a NEW batch of yogurt using the “intense” six-week old yogurt as a starter and I ended up with the most wonderful, sour yogurt I’ve ever had! It’s by far the best yogurt I’ve ever made!
Remaining questions: will the sour notes continue to propagate as I prepare new batches with higher frequency? If the flavor is tied to the starter, can I prepare a batch of yogurt using a shorter incubation period and end up with the same flavor?
Thanks for reading this far! Do you love extra sour yogurt as much as I do? Let me know what has worked for you!
