A classic French onion soup, with a few tweaks to make it healthier.
Thinly slice the onions.
Put the onion and sugar into a pan with some oil and cook for around 45 minutes - NO LESS. The onion should be very soft and sweet, and if using yellow onions, golden brown.
Add the flour and stir for a few minutes.
Add the boiling stock and the wine and bring to a boil.
Simmer gently for around 45 minutes, stirring occasionally.
Put the cheese slices on top of your bread and put it under the grill for 5 minutes, until the cheese is melting.
Put the soup into bowls and top it off with the bread slices.
Increase the cooking times of each 45 minute section up to an hour for an even richer soup.
You can change the kind of wine you use and also add additional liquids such as brandy for more of a kick.