Bring a pot of water to boil. Add onions and boil for 2 minutes. Drain. Once cool enough to handle, slice off stem and pop the onions out of the peel.
Heat olive oil in pan. Add onions and sauté for 5 minutes, until golden.
Add sugar, water, and wine. Bring to a boil then lower heat to medium. Cover pan and cook until liquid is almost absorbed, about 20 minutes. Uncover towards the end so you can keep an eye on the onions (don’t overcook).
They should be super tender and melt-in-your-mouth at this point. Keep them in a tightly sealed container in the refrigerator! They’re easy to rewarm before serving (briefly in the oven will do the job).