This classic French bistro soup is my Mum's favourite so I often find myself making a batch.


  • 50 g butter
  • 675 g onions (thinly sliced)
  • 1 tblsp sugar
  • 25 g plain flour
  • 1 l brown chicken or beef stock
  • 1 tblsp cider vinegar
  • 1 small baguette (cut into slices)
  • 100 g carrigaline cheese (waxed removed and thinly sliced)
  • 2 tsp chopped fresh parsley
  • salt and freshly ground black pepper


  • If you have heatproof serving bowls, fill with the piping hot soup and float the cheese-covered baguette slices on top and then grill until the cheese is bubbling and melted. Here I've used a semi-hard waxed cheese from Cork, but really any Irish cheese would work well, even cheddar.
  • Melt the butter in a large pan and add the onions and sugar. Cook the onions over a very low heat for about 15 minutes until well softened and golden brown, stirring occasionally so the onions do not stick as they caramelise.
  • Stir the flour into the onion mixture and cook over a very low heat for another 5 minutes, stirring continuously.
  • Gradually pour in the stock and add the vinegar, stirring to prevent any lumps forming.
  • Bring to the boil, then reduce the heat and simmer for 15-20 minutes until the onions are meltingly tender and the soup has thickened, stirring occasionally. Season to taste.
  • Preheat the grill to high. Arrange the baguette slices on the grill rack and toast on both sides.
  • Arrange the cheese on top and cook for another 1-2 minutes until bubbling and melted. Sprinkle the parsley over.
  • To serve, ladle the soup into warmed serving bowls and arrange the bubbling cheese toasts on top.