Onion Tart (Zwiebelkuchen)

Zwiebelkuchen is the German answer to quiche, and in many ways it’s better. Sauteed onions and crispy diced bacon spread over a homemade butter pastry crust, then covered in a savory egg and whipping cream custard. Baked until set and golden, it’s traditionally served warm alongside new wine during autumn festivals in Germany’s wine regions.

The pastry dough is a simple short crust: butter worked into flour with an egg and half-and-half until it just comes together. Resting it in a cool place for a few minutes relaxes the gluten so it rolls out without springing back. Pricking the bottom with a fork prevents puffing during the initial bake.

Frying the bacon first and then sauteing the onion rings in the rendered fat for just 2-3 minutes keeps the onions soft but not brown. You want their sweetness to come through, not compete with caramelization. The cream custard poured over the top sets during baking, binding everything into a silky, savory filling.

Chef Tips

• Drain the excess bacon fat after sauteing the onions. Too much grease makes the custard greasy and the crust soggy
• Cover with foil for the first 20 minutes of baking to prevent the custard from browning before it sets
• The tart is done when the custard is firm and no longer jiggles in the center
• Let it cool for 5 minutes before cutting. The custard sets up a bit more and slices cleaner

Variations

• Add a teaspoon of caraway seeds to the onion mixture for a more traditional Swabian flavor
• Use leeks instead of onions for a milder, more delicate version
• Sprinkle Gruyere or Emmentaler cheese over the filling before baking for a cheesier tart