Onions can be tricky to grow well from seed, which is why a farmer's onions have long been considered a litmus test for agricultural skill. Hence the expression I recently heard an old-timer use: "He knows his onions." Meaning if the onions are good, the rest of the farm usually is, too.
Knowing one's onions in a literal sense is a great thing to aspire to, and this applies as much in the kitchen as it does in the garden. Onions are absolutely fundamental to cooking. I may love garlic more, but I need onions. When I'm in the kitchen, I know my onions like Adam knew Eve. I don't just use them, I make love to them.
This time of year presents unique opportunities for onion-knowers because last year's crop is starting to sprout. In your pantry, on the counter, in mesh bags at the local grocery store, the onion's yearly urge to grow will no longer be denied.
At the very least, what you need to know is that you should give your prospective bulbs another squeeze before putting them in the cart, because onions usually soften as they sprout. And if you find yourself with some sprouting onions on your hands, it's worth letting them do their thing on the counter.
The sprouts are edible, and taste like scallions. Both sprouted onions and scallions, which are grown from seed, are forms of green onion, and for culinary purposes are virtually identical. Unlike the flesh of the onion bulb, which rarely steals the show in a meal, green onions often stand out, adding bitter pungency where bulbs add sweetness. Green onions are at their best when served raw, when they taste sharp and spicy, and have a bright green radiance. Just a few thin slices of green onion on your miso soup, for example, will crank up the contrast and make it significantly more interesting.
Those with garden space should plant their sprouted onions and watch them grow into rejuvenated, non-rotting versions of themselves. Depending on the onion, and when you plant it, you might get a full-sized bulb again, or a small bulb with a stunningly beautiful flower attached.
Those without dirt can place their sprouting onions on the windowsill. There you can enjoy their beauty, and do a little pruning anytime you need some green onion pizzazz in your food. If you're really into it, plant the sprouting onions indoors in pots.
If you happen to find a sprouting onion bulb that's still firm, it's possible to carefully cut the bulb from around the sprout, leaving the roots at the bottom of the bulb attached to the sprouted part. The firm flesh of the bulb can be eaten, while the sprout can be planted.
While there is adventure to be had in the pursuit of onion greens, casting off in search of half-rotten root crops is not everybody's idea of a good time. An important part of knowing one's onions is knowing one's limitations. Even if the greens of sprouted onions aren't in your cards, their scallion cousins are coming into season at the farmers market.
Knowing your onions can mean a lot of things, like how to cut them without crying, how to caramelize them without burning, and what raw onions — bulb or green — do in conjunction with browned meat. (Hint: it's awesome.) To know your onions is more than how you grow, cook, and eat them, it's remembering how much you need them, and being grateful.