Tahini is one of those ingredients that either camps out in my pantry for months, or I use it up in a matter of weeks. Since I'm going through the later phase, paying $11 for a small jar of roasted, organic tahini instigated a DIY project.
1.5-lbs of organic, hulled sesame seeds set me back $6. Since I prefer the deep, nutty flavor of roasted tahini, I opted to toast the seeds. In retrospect, I could have turned on the oven, but turning on the oven for such a small amount of seeds seemed wasteful.
After 20 minutes on medium heat, the seeds were toasted, albeit unevenly, and ready to blend.
If you do this at home, let the seeds cool. I didn't do this, so I ended up taking 2 sessions to blend the seeds because the container was hot to the touch.
The sesame seeds started off dry and I wondered if I needed to add oil. However, as I continued to blend and scrape down the sides, more oils came out and the mixture became cohesive.
After a few more minutes, the tahini was a smooth butter. Success!
Using 1.5-lbs of raw sesame seeds resulted in roughly 24-ounces (3 cups) of tahini, 50% more than the the jars of tahini I had been buying at the store. So, if I were to buy this, it would cost me $16.50 versus the $6 I paid at Berkeley Bowl West. I love it when a little experimentation leads to a better, cheaper solution!

