Expired Tahini is safe and OK to use as long as it has not actually gone bad.
If the Tahini still smells good, tastes good, has no mold in it etc then the expired Tahini is safe to use.
Expiration of Tahini or other foods or condiments does not mean they are actually bad but they are not as fresh as they would be before expiration.
I've used expired Tahini before and never got sick.
Tahini is supposed to be somewhat bitter tasting.
Bitter Tasting Tahini is normal and it does not mean that it's bad.
Some brands of Tahini are more bitter tasting than others which is also normal.
Tahini is good for up to 2 months after opening.
When sealed the Tahini is good for up to 6 months before it loses it's freshness and may not taste as good.
It will remain safe to use after 6 months of being sealed but it's best to use the Tahini within 6 months even though it has not been opened.
Tahini is a condiment made from toasted ground hulled sesame.
Tahini is sometimes served by itself or as a major ingredient in hummus, baba ghanoush, and halva. Tahini is used in the cuisines of the Levant and Eastern Mediterranean, the South Caucasus, as well as parts of North Africa.
Tahini can remain at room temperature even when opened or be refrigerated.
Tahini does eventually go bad and so it's best to use it within 6 months.
If you notice a bad smell to it or there is any mold in it then throw it out.