Produce
Chopped Onion
Chopped onion is one of the more complete entries on this site, with real data across all three facets — conversion (160g per cup, roughly one medium onion), substitution (onion powder, shallots, or leeks, each suited to different uses), and storage (7-10 days refrigerated, 10-12 months frozen with a texture change).
What ties these three together is onion's dual role in the kitchen: it's foundational enough to nearly every savory dish that getting its conversion right matters for recipe scaling, common enough to run out of that a real substitute list is genuinely useful, and used often enough in bulk-prepped form that its storage and freezing behavior comes up constantly in practice.
The freezing note is worth highlighting specifically since it connects all three facets: frozen chopped onion (good for 10-12 months) softens in texture, which is exactly why it's recommended for cooked dishes rather than the raw applications (salad, fresh salsa) where onion's crisp bite and sharp flavor are the point.
Onions release a sulfur compound when cut that irritates the eyes, a genuine chemical reaction (not an urban myth) triggered by an enzyme reacting with sulfur-containing compounds stored in the onion's cells — chilling an onion before cutting, or cutting it under running water, are both real, if imperfect, mitigation techniques.
Yellow, white, and red onions differ meaningfully in sharpness and sweetness despite similar weight and volume — yellow onions are the standard all-purpose cooking onion in most US recipes, while red onions are milder raw and more commonly used uncooked in salads and quick pickles.
Caramelizing onions low and slow over 30-45 minutes triggers the Maillard reaction and breaks down the onion's natural sugars into a deeply sweet, jammy result — a genuinely different flavor and texture from a quickly sautéed onion, worth the extra time for dishes like French onion soup where that depth matters.
Frequently asked questions
How much chopped onion does one medium onion yield?
Roughly one cup — a useful rule of thumb connecting the whole-onion instruction many recipes give to the cup-based conversion figure (160g/cup) this site uses.
What's the best onion substitute if I need texture, not just flavor?
Shallots or leeks — both keep a genuine allium texture, unlike onion powder, which trades texture away entirely for pure flavor; the trade-off is that both are milder and sweeter than standard cooking onion.
Should I freeze chopped onion raw, or cook it first?
This site's guidance covers freezing it raw (10-12 months), with the note that texture softens on thawing — either way, frozen onion is best suited to cooked dishes rather than raw applications regardless of whether it was frozen raw or pre-cooked.
Does this hub page distinguish between cooking onions and sweet onions like Vidalia?
Not as separate entries — both are close enough in density and general kitchen behavior to share this page's conversion figure, with the main practical difference between them being flavor sweetness rather than weight or storage life.
Is there a separate page for whole, unchopped onions?
No — this site's conversion and storage data is specifically for chopped onion, since that's the form most recipes actually measure by volume; whole onion storage follows a longer, different timeline better suited to pantry-style guidance than a cup conversion, and generally outlasts the same onion once it's been cut.
Does this hub page connect to a broader produce category page?
Yes — the Produce category hub covers onion alongside the rest of this site's fruit and vegetable ingredients, with broader context on how cutting and water content affect measurement and storage across the whole category, not just this one entry.