Gluten-Free Lemon Tart
1/3 cup rice flour, plus extra for dusting pan
1/3 cup potato starch
1/3 cup tapioca starch
1/4 cup sweet rice flour (also called glutinous rice flour)
1 tablespoon xylitol
½ teaspoon xanthan gum
¼ teaspoon salt
6 tablespoons cold, organic butter
2 teaspoons vanilla extract
1 large egg
2 large eggs
2 large egg yolks
2/3 cup xylitol
Zest of 2 lemons
2/3 cup lemon juice
½ cup crème fraiche or sour cream
Cut the butter into small pieces and return to the refrigerator until needed. To make the crust, start by heating your oven to 350 degrees. Coat a 9-inch tart pan with cooking spray and a dusting of rice flour. Combine the remaining flours and starches with xylitol, xanthan gum, and salt in a large bowl. Cut the cold butter into the mixture with the help of a pastry cutter, then work in the vanilla extract and egg.
Once the dough has come together to form a ball, knead it briefly to finish, making sure to not overwork the dough or to melt the butter. Between two sheets of waxed paper, roll out the dough to a diameter of 12 to 13 inches. Peel the waxed paper away from one side of the dough and drape over the tart pan with the remaining sheet facing up. Peel back the second sheet, then press the dough into the pan, making sure it is even. Bake the empty shell for 10 minutes, then set aside to cool while you mix the filling.
Whisk together the eggs, yolks, and sugar in a bowl, just until evenly distributed, then stir in the lemon zest and juice. Add the crème fraiche or sour cream last and whisk until the mixture becomes smooth. Fill the cooled tart shell with the lemon mixture and return the tart pan to the oven for 15 to 20 minutes, just until it is set. Remove from the oven and let it cool. Finish the tart with a dusting of powdered sugar.