Leek and Mustard Tart
 
Ingredients
  • For the tart shell:
  • 7 ounces cold, unsalted butter
  • 2¼ cups all-purpose flour
  • ½ tablespoon sugar
  • 2 teaspoons salt
  • ½ cup ice water
  • 1 tablespoon lemon juice
  • For the filling:
  • 2 leeks, halved lengthwise and then sliced thinly
  • 1 tablespoon olive oil
  • 2 eggs
  • ½ cup cream
  • ½ cup milk
  • 4 teaspoons Dijon-style mustard
  • Salt and pepper to taste
Instructions
  1. Cut the butter into small cubes and place half of the cubes in the freezer. Return the other half to the refrigerator until needed.
  2. Combine the flour, sugar and salt in the bowl of a food processor and pulse a few times to mix. Add the chilled butter from the refrigerator to the dry ingredients and process until the mixture resembles coarse meal.
  3. Add the frozen butter to the food processor and pulse until the butter is in small but still visible pieces.
  4. Combine the lemon juice and ice water and add six tablespoons of the mixture to the ingredients in the food processor. Pulse several times until combined. Pinch a bit of the dough and if it holds together, you do not need to add more liquid. If it is still dry, add more of the liquid, one-half tablespoon at a time. Remove the dough to a bowl or a well-floured board.
  5. Knead the dough until it forms a ball. Divide the dough into two and wrap each half well in plastic wrap. Place half the dough in the refrigerator to relax for at least a half-hour. Reserve the other half for another use.
  6. (If your dough was chilled for longer than thirty minutes, remove from the refrigerator and allow to soften for ten to fifteen minutes before rolling it out.)
  7. Prior to rolling out the dough, strike it with your rolling pin to flatten. This will soften it further.
  8. Preheat the oven to 400 and grease the bottom and sides of a tart pan.
  9. Liberally dust a pastry board or mat and your rolling pin with flour - you can use rice flour which does not contain any gluten to keep the dough tender, but all-purpose flour will do.
  10. Roll the dough out, rotating it and turning it frequently and adding more flour as necessary to keep it from sticking, until it is the size of your tart pan and between ¼ and ⅛ of an inch thick.
  11. Carefully center the tart dough in the pan and press it into the bottom and sides. Trim or fold over any excess dough around the edges. (If time allows, chill the dough in the pan prior to baking. If doing ahead, the dough can be refrigerated or frozen in the pan overnight.)
  12. Cover the dough with aluminum foil and fill with pie weights, beans or raw rice.
  13. Blind-bake the crust for 20 minutes. Then remove the weights and foil and bake an additional three minutes.
  14. Remove the crust from the oven and cool on a rack. Raise the oven temperature to 425.
  15. Prepare the filling by sautéing the leeks in the olive oil over medium heat until soft, about ten minutes. Season well with salt and pepper.
  16. Meanwhile, in a medium bowl, beat together the eggs, milk, cream and mustard.
  17. Place the softened leeks in the bottom of the pre-baked tart shell and spread in an even layer.
  18. Carefully pour the custard over the leeks. The custard should almost reach the top of the pan, but do not overfill.
  19. Sprinkle the tart with salt and pepper and bake for thirty minutes.
  20. Cool the baked tart on a rack for a few minutes before cutting.
  21. Serve warm or room temperature.
Notes
This recipe makes two balls of tart dough but only one is needed for this recipe. Reserve the remaining ball of dough for another occasion. Well-wrapped, it may also be frozen.
Recipe by West of the Loop at https://www.westoftheloop.com/2014/10/22/leek-mustard-tart/