More often than not I’m cooking what I have on hand rather than going on a special shopping trip for ingredients. This is why onions, carrots, potatoes, squash, cabbage and turnips are the unsung heroes of the dinner hour. They aren’t glamorous but they are there for you in your hour of need. Onions are so self-sufficient that they can support an entire dinner and still be appreciated the next day at lunch. The smell of a frying onion comforts and reassures your dining companions that indeed, something is happening in the kitchen. They’re humble, versatile and surprisingly complex. Recently I had raw onions served as a side to cassoulet and they worked much like lemon in that the crunchy raw slices brightened the rich meaty flavours of the beans and duck.

So why not let the onion take centre stage with a simple, filling and yet somehow exotic onion and leek tart? The beauty of this tart is that you can use onions and/or leeks, even throw in some diced shallot or garlic, or stick to all leeks or all onions. From there you can add bacon lardons, cream or crème fraîche and, if desired, your choice of cheese like Gruyère, Comté or Cheddar.

The onion tart is a versatile thing of magic. It’s rich and savoury with a subtle sweetness from the long-cooked onions. It is delicious served hot with a green leaf and walnut salad, as a cold lunch, is an excellent addition to a brunch and welcome on any buffet.

To make this recipe you will need a 12” shallow tart dish, two frying pans, parchment paper and dry rice or beans for blind baking the crust.
Author Karen Ralph


  • 1 pkg frozen puff pastry
  • 3 leeks trimmed
  • 2 medium yellow onions diced
  • 3 tbsp butter
  • 1 tbsp olive oil
  • 2 large eggs
  • 1 cup heavy cream
  • 1/2 cup white wine
  • 1 cup grated cheese Comté, Gruyère, Cheddar, Pecorino
  • 1/2 cup bacon lardons 6 bacon strips cut crosswise into matchsticks, also optional
  • Thyme leaves, tarragon or rosemary finely chopped
  • 1/2 tsp chili flakes optional


  • Thoroughly thaw puff pastry. Pre-heat your oven to 425°F and butter your tart dish.
  • Roll your puff pastry out to ⅛” thickness and press it into the tart dish, rolling any overhanging excess dough into the rim.
  • Prick the dough multiple times with a fork and lay the sheet of parchment paper on the dough.
  • Fill the paper with dried rice or beans and bake the crust for 15 minutes.
  • Remove the dish from the oven and carefully lift the parchment with riceor beans off of the crust. The beans and rice can be stored in a ziplock bag and used multiple times as blind baking pastry weights.
  • Put the crust back in the oven for another 10 minutes and allow it to slightly brown. Remove from oven and set aside until ready to fill.
  • Turn your oven up to 450°F.
  • Trim your leeks by cutting off the green parts about 2" from where the white ends and cutting off the root.
  • Slice the leek lengthwise and rinse thoroughly under running water – leeks are notoriously sandy and that’s one ingredient you don’t want. Once clean, slice the leeks crosswise.
  • Peel and dice your onions and set the leeks and onions aside. If you are using bacon, slice the bacon strips crosswise into lardons, and set aside.
  • Heat the butter and olive oil in a medium sized frying pan.
  • When the butter and oil are hot and foaming, add the onions and leeks and stir until they are coated with butter and oil and turn the burner down to medium. Add the wine.
  • Cook the leeks and onions until they are soft, translucent and tender or go further and caramelize them. They will turn a rich, golden brown with a soft, melting texture and sweet earthy flavour.
  • Caramelizing takes time but the deep umami flavour that this adds to the tart makes it well worth the effort. Once your onions and leeks are well under way, fry the lardons on medium heat until they’re nice and crispy, drain them on a paper towel and set aside.
  • In a medium bowl, mix together the cream, eggs, cheese, chopped herbs and chilis.
  • Thoroughly combine the fried bacon with the leeks and onions and scrape the mixture onto the crust, spreading evenly. Evenly pour the cream, cheese, egg and herbs over the leeks, onions and bacon.
  • Place the tart in the 450°F oven and bake for 10 minutes.
  • Turn the heat down to 425°F and bake another 15 minutes until the crust is golden brown and slightly puffy.
  • Remove from the oven, cool slightly, cut into wedges and serve with a green salad topped with walnuts and a tart vinaigrette.