*Some recipes have you use only 1/4 cup of tahini for this much hummus, which makes the sesame flavor very unobtrusive. I like the sesame hit from this larger amount and also from the addition of sesame oil. Various authentic recipes give recommendations for authentic tahini, but those brands are often available only at a Middle Eastern grocery store or online. Poor quality tahini can be bitter (which may be caused by rancidity of the sesame seeds) or so badly separated that it's almost impossible to re-combine. If you just want to buy what's on the shelf, look to see if there's a lot of oil on top, an indication that the product has probably been sitting for a long time. Some brands don't come in clear containers, though. In general, I think it's probably fair to say that with the popularity of this ingredient there's been an uptick in quality. Try smelling and tasting a new brand/jar before using it. If it seems off, take it back.
**I always point out that I just use bottled citrus juices. If you do use fresh lemon juice, a good-sized juicy lemon may give you as much as 1/4 cup. I have a more generous allowance of lemon juice than most recipes.
***If you use fresh lemon juice you might as well use the zest, too, being sure to zest the fruit before slicing and juicing. (You knew that.) If you're using bottled juice and want an extra hit of lemon flavor, use the lemon oil. Best way to keep this and other types of citrus oils on hand is to buy Boyajian Inc Boyajian Assorted Pure Citrus Oil, Set of 3 and keep them on hand in the fridge. You use so little at a time that your set of tiny bottles will last you months if not years, and it keeps forever. (Amazon affiliate link)
****Sad to say, you'll never get the full whipped effect for this recipe unless you have a high-speed blender. But I refuse to buy an appliance that I have no other need for. Hey, Smitten Kitchen uses a food processor, and her stuff looks great. Just be sure to give the final mixture 2-3 minutes of processing before you declare it finished. (My mother-in-law, bless her, says that I can use her VitaMix blender the next time I make a batch. Stay tuned.)