They're a critical ingredient for Fuschia Dunlop's ma po tofu recipe (she doesn't say they're critical, but I say they are).
I'm often disappointed as these are sometimes hard to find. I've found them in several different supermarkets (many of the 99 Ranch stores, SG Superstore, 168 Supermarket), but it's strictly hit-and-miss. My most recent failure was yesterday at the Garvey/Atlantic 99 Ranch.
Is there a season for these vegetables? Any tips to help me find them more consistently?
For reference, this is what they look like. Although they look like a narrower version of western leeks, the dark green part of the leaf is tender and edible. Additionally, it has a pungent garlicky aroma and flavor compared to the mild sweetness of a western leek.