When Ernst and I got married in Germany 36 years ago, Onion Tart (or Zwiebelkuchen) was the very first recipe I requested from an old German lady who served it with great confidence to her customers and friends. Ernst studied in Schwabenland, a wine-growing region in South-Central Germany around Stuttgart, where the people speak a specific German dialect - which Ernst naturally picked up and still speaks to perfection. During the grape harvest in Fall, the Schwaben serve onion tart with a young, fresh, unfiltered white wine, called Federweisser.
A typical Schwabish onion tart is baked in a flat rectangular baking tin (2-3 cm deep) and served in squares. The recipe I obtained form the old lady years ago has become a firm favourite of our family and it gives me great pleasure to share it with you!
For the pastry:
250 g cake flour (or all-purpose)
180 g cold butter, diced
2,5 ml (1/2 teaspoon) salt
30-45 ml (3-4 tablespoons) iced water
For the filling:
4-5 large brown/white onions, peeled
30 ml (2 tablespoons) extra virgin olive oil
200 g Mozzarella cheese, roughly grated
250 ml (1 cup) fresh cream
3 XL eggs
a pinch of salt
freshly ground black pepper
2,5 ml (1/2 teaspoon) cumin seeds (or aniseed)
For the pastry: Place the flour, butter & salt in a food processor and pulse until it resembles rough breadcrumbs. With the motor running, add the water one tablespoon at a time until it just starts to come together in a ball. Remove from the processor, press together in a smooth ball, then cover with plastic wrap and refrigerate for 30 minutes.
For the filling: While the pastry is chilling, preheat the oven to 220 C (425 F). Slice the onions horizontally into 1cm thick slices. Place on a lined baking tray, drizzle with olive oil, then season lightly with salt & pepper. Roast for 30 minutes, then remove from the oven. Carefully turn each sliced of onion over - they should be darker on the bottoms. Set aside.
For assembly: On a floured surface, roll out the pastry with a rolling pin to a thickness of about 3 mm. Line a greased tart tin (about 27 cm diameter x 3 cm deep) with the pastry and neatly trim the edges. Bake blind for 10 minutes then remove from the oven. Spread out the grated cheese on the bottom of the pastry. Arrange the roasted onion slices tightly all over. Whisk the cream and eggs with a pinch of salt & pepper, then pour the mixture all over the onions. Sprinkle with cumin seeds, then return to the oven for about 30 minutes or until golden brown and cooked.
Serve warm with chilled, fresh, dry white wine – my personal favourite for this very special onion tart is the Ernst Gouws & Co Chenin Blanc. Serves 6 as a light meal.