Ingredients:
- 4 huge onions, peeled and sliced
- 2 tablespoons flour
- 2 tablespoons oil or butter
- 4 pints beef stock (dissolved stock cubes or 2 teaspoons Marmite, dissolved
- salt and pepper
- thick slices of mature French bread or Vienna loaves
- 110 g (4 oz) grated gruyere cheese