4 large onions (I used 2 red and 2 white)
1-2 tbs olive oil
1-2 tsp Balsamic vinegar
1 tsp flour (cornflour if you need to be gluten-free)
1 litre water
1 Knorr Vegetable Stock Pot
Seasoning to taste
Toasted cheese, ideally Emmental, ideally on a chunk of baguette (but ordinary cheese on toast will do); 1 slice per bowl.
Peel and slice onions and place in a heavy-bottomed pan with the olive oil and balsamic. Cook on a low-ish heat for about 30 minutes, stirring occasionally. When the onions are soft and colouring, add the flour and stir well for a few seconds until the flour browns. Now add the water and Stock Pot (of if you are that way inclined, you could use a litre of your own home-made stock), adjust the seasoning (I used salt, pepper and soya sauce). Bring back to the boil and simmer for 5 minutes or so while you make the cheese on toast. Place a slice of cheese on toast into a big soup bowl and pour the boiling soup over it.