Ok. Have written it up. Here goes:
Use your super frickin duper mandolin to slice up 800g of onions (give or take 50g). They need to be sliced, not chopped, so if you don't have a mandolinthen be patient and slice them as thinly as you can
Melt 50-60g of butter til it bubbles but doesn't burn. Turn the heat down and add the onions. They will need to cook very slowly for a good hour. Stir regularly. They must not burn so keep it so low you can hear them cooking, but not high enough that you can see them cooking. Keep stirring. Every two or three minutes.
Take two beef stock cubes, I used low fat maggi but any good quality will do. Boil them in 1.5l of water. Once disintegrated add 250 ml of dry white wine. Switch off the heat.
Don't forget to keep stirring the onions, which should now be much reduced. Don't burn them. Stir, leave, go back to stirring etc.
Mix four small or three large cloves of garlic, crushed, with 30g of flour.
Leave to one side.
You now have your onions reducing on a low heat. Your stock is ready, your flour and garlic ready. Now grab one or two bay leaves and put next to the flour/garlic.
Once your onions have been reducing, with regular stirring for about an hour, add the flour and garlic and stir until you can't see the flour anymore.
Take a ladlefull of your stock/wine mix and put it into the onions. Add a good pinch of dark brown sugar and up the heat, stirring so the brown sugar almost boils (but the onions don't, you really have to stir at this point, lifting the pan from the heat if need be. It only takes a few (3?) minutes but you can't leave it). Once the liquid is almost gone turn the heat right back down again. Add the rest of the stock/wine mix, stirring all the while. Nothing should burn. Onions and sugar especially.
Add the bay leaves. Taste for seasoning. Stock cubes are pretty well seasoned so I didn't add any salt or pepper.
Bring to simmer, cover, turn down to low simmer. Leave, stirring occasionally, for a good hour.
To serve: dry baguette or the best stale bread you can find, cut into cubes. The French grill the soup with cheese on baguette. But honestly, as gorgeous as that is, the girls found the cheese too much so, cubes of bread in the bowl. Parsley and pour the soup over that. The bread will rise, mush up and be yum. Here is when you sprinkle cheese and grill if you want. But we chose not to and it worked out better.
Here's where you flame me. It's taken me years to perfect it. I hope I wrote it out ok. For me the key thing is, if anything looks like it is about to burn, lift the pan up, remove, turn down the heat. A burned taste of oneonion ring will ruin it.
Start to finish about three hours but the first hour is preparing ingredients, the second hour is hovering and stirring and the last hour is simmering.