How to Make an Alsatian Onion Tart

Sometimes I think God put puff pastry on Earth for one reason and one reason alone: so it could be made into scraps and those scraps turned into Alsatian onion tart. This appetizer is so rich and lovely — covered with caramelized onions, cream and bacon — odds are excellent your dinner guests won’t ever make it to your main course. So pour the wine, lay out the cheese and nuts and call it a day.

I start with my puff pastry scrap ball (a little brain-looking thing that was previously frozen, now completely thawed). If you don’t collect your own — start! Otherwise some nice flat store-bought puff pastry will do just fine.

Roll it out into a circle of whatever thickness you’d like. I’m rolling mine out as thin as I can because it’s going into a brick oven at very high heat. So, the thinner the better to prevent the center from ending up soft or mushy.

Trim it up however you’d like with a pizza cutter, then dock the dough to let steam out (you don’t want it puffing up very much).

To your small quantity of caramelized onions…

…add your cream or crème fraîche and stir it in. Salt the mixture lightly (you’ll be adding bacon to it later).

Spread it over the dough round (very thinly if you’re using a brick oven, thicker if you’re using a standard oven).

Then sprinkle on your blanched bacon. This is some hog jowl bacon I found here locally (Oh, Kentucky, how do I love thee…?).

Push the coals aside in your Electrolux EZ-Bake brick oven, and sweep the floor. (If you don’t happen to have one of these, simply follow the standard oven instructions below).

Slip the tart onto a lightly floured peel, and jiggle it to make sure it isn’t sticking.

Then slide the tart onto the floor of the oven.

It’ll be ready in under two minutes, provided the oven is well heated (I’d already fired my oven for bread, which is what I baked just after this). The tart should come out blackened around the edges, which is traditional, or so I’m told. Note for brick oven users: you’ll want to pick the tart up with a metal peel, not a wooden one, since there’ll likely be a bit of scraping involved. Onion tarts are wetter and heavier than pizzas, so be prepared.

How did it turn out? Very well. Puff pastry, when it’s cooked that fast, is bound to be at least a little underdone on the top. My guess is that puff pastry was not the original dough for onion tarts back in Alsace. They probably used a leaner bread or short crust dough of some sort, which would make a lighter, though considerably less decadent, tart.

8 thoughts on “How to Make an Alsatian Onion Tart”

  1. Looks great!
    What about scraps of homemade Filo? Do you have any idea about using them? Or would they be too dry to be useful?

    1. Hey Jasmine! I don’t see why not! You might want to bake the pastry on a sheet pan in that case since the base will crumble more easily, but it’s worth a try. I’d suggest going a little lighter on the topping so as not to make the filo soggy. Let me know how it goes!


      – Joe

  2. I am really looking forward to making this. I’ve really enjoyed tarte flambee in Alsace. I think they use more of a thin pizza/bread base don’t they? But then I wouldn’t get the chance to use up my puff pastry scraps ball!

    1. Hey Alison!

      These sorts of tarts can have almost anything as a base. I ate one in Alsace with laminated dough (puff or croissant) base, but I’m sure there are pizza-like versions as well…probably with an enriched yeast dough. I could see it worked well with brioche even. All of which is to say: use whatever is handy! 😉


      – Joe

  3. Hey Joe,

    I was describing making this to a French coworker of mine, and she said it sounded like a Flammenkueche, though she said her mother would make it with a sort of sourdough base and she said it was excellent with sausage and/or potatoes and/or “really stinky cheese” (she suggested muenster) on top. I’d love to try it sometime, though I (and my guests) was(were) more than happy with your version.

    1. That’s exactly what this is, Nick. It’s sort of an Alsatian pizza as I’m sure you’ve intuited, crusts can be just about anything, toppings can be just about anything, though long-cooked onions are the classic as far as I know. Any of those stand-by Alsatian ingredients will work however: bacon, sausage, potatoes…and oh yeah, the stinky cheese. I had the runniest, stinkiest muenster of my life in a little town called Riquewihr in Alsace. Whew! I can still recall the stench. It went great with the bubbly new wine we were all drinking (to excess). I’ll have to add the most readily available equivalent next time I make it!

      Cheers and thanks!

      – Joe

  4. Just made this today with some leftover puff pastry.
    Don’t have a wood fire oven, hence I preheated my cast iron pan for an hour on the highest oven setting. 550°F(288°C).
    My onions were caramelized beautifully, and finished with salt&thyme.

    The flavor was this was fantastic. Thank you once again Joe!
    Unfortunately no pictures. Gobbled it up too quickly.

    1. Woohoo!

      Thanks for the note, Shivam! As punishment for forgetting the photographs, next time you will mail me a slice.

      – Joe

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