pearl onions
Small, mild onions, typically about a half-inch to an inch across, cooked whole rather than chopped because their size lets them hold their shape through long braising or simmering. Much of their mildness comes from being harvested young rather than from a different species. They're used mainly for their shape and gentle sweetness rather than for pungency.
Buying guidance
Look for firm, dry bulbs with tight, papery skin and no soft spots or sprouting green shoots -- a soft or slimy pearl onion has started to rot from the inside. Frozen, pre-peeled pearl onions are a reasonable shortcut, since peeling the fresh ones (loosened by a quick blanch first) is fussy work for something this small.
Substitutions
- Small boiling onions or halved shallots -- close in size and behave similarly in a braise, though shallots are sweeter.
- Diced yellow onion -- loses the whole-onion presentation but works for flavor alone.
Tips & common mistakes
A hard boil rather than a gentle simmer can cause the outer layers to slip loose and the onion to fall apart into rings, defeating the reason for using a whole small onion in the first place -- keep the heat gentle enough to hold their shape through a long, slow cook.
Storage
Their small size gives pearl onions more skin relative to flesh than a regular onion, so they dry out and shrivel in the pantry noticeably faster -- use them within a couple of weeks rather than expecting a large onion's months-long shelf life. Frozen, pre-peeled pearl onions go straight into the pot from frozen without thawing.