I think the correct response to the question is 'till they are done'. I hate it when recipes have timing directions like this, as everyone's equipment is so ver

I think the correct response to the question is 'till they are done'. I hate it when recipes have timing directions like this, as everyone's equipment is so very different. If an onion is larger, it'll take more time to boil off the liquids, if the pan is larger, it will take longer to heat, etc etc. It would be more useful for people to think of cooking as building a catalog of techniques they have mastered, then to apply these in different combinations to different ingredients to achieve the various dishes they want to make. On the subject at hand, cooking onions more or less produces such a variety of tastes and textures, it really is a very important part of cooking many dishes.