Properly diced, and cooked in a heavy pan, you can brown onions in 15 minutes. Most people miss those two important steps though. And recipe authors mistakenly

Properly diced, and cooked in a heavy pan, you can brown onions in 15 minutes. Most people miss those two important steps though. And recipe authors mistakenly think the general population has the proper technique and equipment. Coarsely chopped onion in a dinky frying pan will take much longer.