Thank you earthbabe, it's a pungent gum, like asafoetida, not the purely emulsifying kind. A very special taste!

Of course you got me googling and ta-daaaa! Wikipedia has details of what it is, where it grows, and how to use it!

Now going googling in delis to see if someone stocks it online. Thank you for the nudge!

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SSx
not every situation requires a big onion