For the Onions

  • 3 c onions, sliced thin (about 3 medium)

  • ¼ c + 2 Tbsp chicken broth

  • 2 tsp + 1 tsp balsamic vinegar

  • 2 tsp thyme, dried

For the Crust

  • 2 Tbsp olive oil

  • ¾ c walnuts

  • 1 ¼ c whole wheat flour

  • 1 ¼ c all purpose flour

  • 2 tsp sage

  • ¾ tsp salt

  • ½ tsp black pepper

  • 2 Tbsp sour cream

  • 7-10 Tbsp ice cold water

For the Potatoes

  • 1 ½ lb California sweetpotatoes, sliced ¼ “ thick

  • ½ tsp salt

  • ¼ tsp white pepper

  • 2 generous pinches of cloves, ground

  • 2 Tbsp milk (for brushing the finished tart)

Makes: one 12" tart (serves 4-6)
Prep time: 50 min.
Cook time: 50 min.


  • Preheat oven to 425⁰F.

For the Onions

  • Place sliced onions in a large, non-stick frying pan. Add ¼ c broth and 2 tsp vinegar. Cover and heat over medium-low for 25 min, stirring every 5 min to prevent sticking or burning, until onions are dark and caramelized.

  • Remove onions from heat. Add 2 Tbsp broth, 1 tsp balsamic vinegar, and thyme. Mix well and set aside.

For the Crust

  • While the onions are cooking, prepare the crust.

  • Pour olive oil in a shallow dish. Place in the freezer to firm up while you start the dough.

  • Process walnuts in a food processor until fine. Add wheat flour and process a few seconds.

  • Place walnut mixture in a large bowl. Add all purpose flour, sage, salt, and pepper. Stir to combine.

  • Take olive oil from the freezer (it should be thicker, if not slightly solid now). Cut olive oil and sour cream into the flour mixture until the chunks are the size of small peas.

  • Add 3 Tbsp of ice cold water and cut the moisture into the mixture until it is evenly distributed. Add 3 more Tbsp and mix until well incorporated.

  • Continue adding the remaining water by the Tbsp, kneading the dough with your hands between each addition, until a soft, but firm dough comes together.

  • Wrap the dough in plastic wrap and refrigerate while prepping the rest of the tart.

For the Potatoes

  • *With the onions starting to caramelize and the crust refrigerating, roast the potatoes.

  • Place potatoes on a greased baking sheet. Spray with cooking spray and dust with the salt, pepper, and cloves.

  • Roast at 425⁰F for 10 min. When potatoes are done, reduce oven temperature to 375⁰F.

Putting it all Together

  • Remove crust from refrigerator and roll into a 15” circle.

  • Gently place crust on baking stone, pizza pan, or baking sheet. (The edges will hang over at this point.

  • Leaving a 2” border, spread onions over the crust.

  • Top onions with roasted potato slices. (Again, leaving a 2” border.)

  • Gently, fold the 2” border up over the filling.

  • Brush the tart with milk.

  • Place tart in the oven and tent loosely with a piece of aluminum foil. Bake, tented for 10 min. Remove foil and continue baking for 40 min.

  • Remove from oven and let cool for 5-10 minutes before serving.

*You can prepare your tart elements up to this point ahead of time. Just keep caramelized onions and crust dough refrigerated until you are ready to make your tart.

Recipe courtesy of Curious Cuisiniere

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