Pretty much any meal I cook, before I even do the hunt-through-the-fridge-and-see-what-needs-to-get-used dance, starts with chopping an onion and throwing it in a pan with a little bit of oil on low heat. Can I get perfectly softened, sweetened onions via sous vide? Or will they just break down into some kind of gross jelly? Do onions need to release steam/gas/something as they cook? What happens if I try a whole onion at once, instead of chopping it up?

Basically, I’d like to drop an onion into a sous vide and see what happens.