A Fall Canvas – Truffle Potato and Caramelized Onion Tart

It is always better when food looks good, in addition to tasting good. In upscale restaurants chefs have to be artists on two fronts; each course is a meticulously prepared work of art, not just in terms of flavor combinations, but also as a fleeting, edible painting or sculpture on the plate, pleasing to the eye. A tart, whether savory or sweet, provides a perfect canvas to make an aesthetically pleasing dish, and its crust, like that of a pizza, provides a natural border that acts as a picture frame.

For our annual Early Thanksgiving feast with friends this year I knew I wanted to make a tart, but wanted to come up with one I had never made before. I was thinking about fall flavors, and the combination of truffle and potato came to mind; their earthiness allows them to work together beautifully.

For some tarts the ingredients will be bright and colorful, scattered over the surface of the pastry like the splatters of a Jackson Pollack painting. For this one, I was looking for more order, perhaps like one of Jasper Johns’ interpretations of the American flag. While the colors in this tart are muted – subtle yellows, tans, and browns with flecks of golden puff pastry – I love the organized look of the thinly sliced potatoes overlapping in rows. I find it pleasing, like the neat rows of vegetable plants emerging in my spring garden. I can only imagine how much better it would have looked – and tasted – with thin wisps of black truffle shaved on top.

Truffle Potato and Caramelized Onion Tart

While the flavor combination and ingredients for this tart are of my design, I claim no credit for the technique used to prepare it; that I copied from Bon Appetit’s Butternut Squash Tart With Fried Sage, which I have prepared on at least a couple of occasions for Early Thanksgiving.

The truffle flavor is somewhat subtle. If you want a stronger truffle profile, add an extra tablespoon of truffle oil in place of one tablespoon of butter when caramelizing the onions. Or better yet, splurge on a black truffle and shave it over the top just as the tart emerges from the oven. It would make for a nice visual contrast to the potatoes and puff pastry, and add tremendously to the flavor of the tart.

1 tart, about 90 minutes

2 Tbsp. butter

2 Tbsp. truffle oil, divided

2 large onions, thinly sliced

½ tsp. kosher salt, divided

1 sheet of frozen puff pastry, thawed according to package instructions

2 Tbsp. flour

1 egg beaten with 1 tsp. water

2 Yukon gold potatoes, sliced to about ⅛ inch thick on a mandolin or with a sharp knife

Truffle cheese, optional

Shaved black truffle, optional

1. Melt the butter in a heavy skillet over medium-low heat and add 1 tablespoon truffle oil. Add thinly sliced onions and ¼ teaspoon salt and cook, stirring frequently until the onions are soft and caramelized, about 30 minutes. If the onions are starting to brown and stick, reduce the heat to low and add a tablespoon of water or stock. Remove from heat and allow to cool.
2. Preheat the oven to 375°. Line a large rimmed baking sheet with parchment paper.
3. Gently roll out 1 sheet of thawed puff pastry on a lightly floured surface to a 10 x 14-inch rectangle. Transfer to prepared baking sheet.
4. Brush pastry with 1 large egg beaten with 1 teaspoon water.
5. Spread the caramelized onions in a layer over the surface of the pastry. (If it seems like too many onions, reserve the extra for another use. They are excellent on a truffle grilled cheese sandwich.) Arrange the ⅛-inch thick slices of potato over the onions, overlapping as needed and leaving a ½-inch border. Place another sheet of parchment paper over potato. Set another large rimmed baking sheet over the tart, which will weigh down the pastry dough and steam the potato slices.
6. Bake until bottom of pastry begins to brown and top begins to puff, about 10–15 minutes.
7. Remove top baking sheet and discard top sheet of parchment paper. Brush potato slices with 1 tablespoon truffle oil and season with ¼ teaspoon kosher salt. Return tart, uncovered, to oven and bake until pastry is deep golden brown and cooked through, about 25–30 minutes. If using truffle cheese, sprinkle over the top of the tart and allow to melt during the last few minutes of cooking. If using black truffle, shave over the tart when it emerges from the oven.
8. Serve tart sliced, warm or at room temperature.

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