Peyajkoli or peyaj-kali are the shoots that the onion plant produces when it flowers. Peyajkoli looks similar to green onions or scallions, but you can differentiate them by the white flowers at the end of the stalk, as well as their beefier build. After pollination these flowers produce seeds that resemble nigella seeds—which is why many people call nigella seeds "onion seeds" (even though they are not the same).

Peyajkoli appears in the markets of Bengal in early November and stays on till January. Since a lot of peyajkoli is consumed here, there are certain varieties of onion that are cultivated in West Bengal and Bangladesh particularly for the blossom stalks. These varieties produce peyajkoli much more quickly than regular onion varieties, even though their onion bulbs are small and are usually only used for growing new plants.

Besides peyajkoli this recipe uses a few of Bengal's winter favourites—sheem or flat beans, tomato (because unlike cooler countries, winter, not summer, is the season for tomatoes in the Indian plains), and coriander (the flavour of winter coriander is very different from the stuff that we find all year 'round now in the markets).

We like to keep the peyajkoli a little crunchy, but many people cook them longer so that they turn softer. Not all families add flat beans to this recipe, but they are a nice addition. The flavour of peyajkoli is somewhere between that of onion and garlic, somewhat like shallots. So a clove of garlic, roughly chopped, complements the flavour, but can be skipped. The tomatoes, besides adding a hint of acidity, give the stir fry a bit of a body. The tomatoes are optional too.