French lentil and onion soup

French lentil and onion soup with cheesey croutons

The weather in Sydney has been crazy lately – first there was the record breaking heat in January, in February we were lulled into complacency by autumnal mildness only to be hit with a blast of heat and humidity around the middle of the month. On the first of March there was snap into cool rainy weather that made it feel like winter was already here.  It’s been hard to work out what wear let alone cook with all this climatic chopping and changing. Faced with the prospect of a cold and rainy weekend I decided to seize the opportunity to make soup. Not just any soup but French lentil and onion soup, which is rich and cosy enough to sustain you in the depths of winter but with the added zing of lemon and mint still feels light enough when it’s cool but not freezing – the perfect trans-seasonal soup.

I first made this soup last winter when I was having my neighbors over for a weeknight dinner, I made macaroni and cheese for the kids and this soup for the adults. When my son found out I was making onion soup he lost all appetite for boring old macaroni cheese and insisted on being served only onion soup. He was quite peeved that I had intended make him eat kids food when there was something so much more interesting on the menu. He had a similar accusatory tone to that he uses when he tells me ‘he’s starving’ as if I haven’t been feeding him properly for the last couple of years.

Sliced onionsFrench lentil and onion soup in pot

I don’t quite know what captured his imagination about French lentil and onion soup. He’d just started reading the Asterix books and was quite taken by the village feasts of steaming cauldrons of stew, piles of peasant bread and wild roast boar.  Perhaps he thought onion soup had a bit of an ancient Gaulish vibe. During that time he’d drawn up and labelled lists of the foods he wanted for his birthday dinner, all of which predominately featured cartoon-style legs of wild roast boar. By the time his real birthday rolled around roast boar was off the menu and the only thing he wanted for his celebratory dinner was French lentil onion soup. When I suggested his friends might like pizza as well, he conceded he might have a little bit of pizza but he really just wanted onion soup.

My son might be a little unusual but when you really think about it there is no reason for kids not to love onion soup.  Loads and loads of finely sliced onion slowly cooked in butter to a mellow, unctuous deliciousness. You have to use real butter for this recipe. There other more middle eastern style onion soups out there that don’t need butter but they don’t have the luxuriant simplicity of French onion soup. Even though this soup has a slightly healthier, lighter vibe with the addition of lentils, lemon and mint don’t be fooled into thinking you can leave the butter out or replace with some kind of non-dairy substitute.

French lentil and onion soup

I love the cheesey croutons that traditionally go with onion soup but my son often prefers to eat it as the ancient Gauls would have, with hunks of plain bread to dunk in it.

Eating French lentil and onion soup and reading Asterix

French lentil onion soup.

Serves four as a meal

Adapted from the Sydney Morning Herald – Good Food Guide

  • 55g ( ½ stick) butter
  • 4 medium brown onions peeled and finely sliced
  • 4 garlic cloves peeled and sliced
  • 1.2 litres of vegetable stock plus more if required
  • 250grams of French style (puy) lentils, washed
  • Handful of fresh parsley leaves roughly chopped
  • Handful of fresh mint leaves chopped
  • Zest and juice from 1 lemon
  • Salt and freshly ground black pepper.
  • 1 small French baguette thickly sliced
  • 150 grams of Gruyere cheese grated
  1. Heat butter in a heavy based pot.  Add sliced onions and cook for about 20 minutes until sticky and golden.  Add garlic and cook for a few more minutes until butter is soft and translucent.
  2. Add stock, bring to a simmer then add lentils and simmer for 30 to 45 minutes until lentils are tender but still holding their shape. If soup is too thick add extra water or stock.
  3. Remove from heat and add parsley, lemon zest and juice.
  4. Season with salt and pepper and garnish with fresh mint to taste.
  5. To make cheese croutons grill one side of bread, add grated cheese and grill on the other side.


  1. Elizabeth this looks delicious. Can’t wait to make it.

  2. I made this the other night for dinner – it was delicious! I love the addition of lemon juice and zest. The only thing I did differently (being a carnivore) was use chicken stock instead of vegetable stock.

  3. Simple & hearty soups like this are #1 on my list! It’s summer here, and I still want some. 🙂

  4. Penniless Veggie says:

    Really impressed by this simple but perfect combination of caramelised onions and french lentils. I’m afraid I did use non-dairy spread, I also used a rich brown vegetable stock made up from Veggiemite, a splash of balsamic and a little brown sugar to bring out the caramel.
    The soup was great, just right for a rainy September day! Will make this again. Thanks 🙂

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