A variation of classic French Onion soup
In a deep pot heat the oil and butter, adding the onions and salt and fry for a few minutes on high
Lower the heat and continue to fry for 30mns stirring occasionally
Add the Soy,Balsamic and Mustard and stir,continue to fry for a few mns
Add the pepper,stock cubes and boiled water, stir and once the pot reaches a rolling boil reduce heat to a gentle simmer
Simmer for 15 mns with lid on.
Serve with croutons or flatbread- I used herby garlic butter and mature cheddar on mines-recipe for basic flatbreads on the website
Tip-if using Balsamic vinegar add 1tsp of sugar- omit this if using glaze