In a mixing bowl, whisk together the gluten-free all-purpose flour blend, xanthan gum, salt, and granulated sugar until well combined.

Cut the cold, cubed unsalted butter into the flour mixture until it resembles coarse crumbs with pea-sized pieces of butter.

Combine ice water and lemon juice, then drizzle into the flour and butter mixture and stir gently until a shaggy dough forms.

Transfer the dough to a floured surface, shape into a rectangle about 1/2 inch thick, and fold into thirds like a letter. Repeat this rolling and folding four more times.

Wrap the dough tightly in plastic wrap and chill in the refrigerator for at least 30 minutes.

Preheat the oven to 400°F (200°C). Roll out the dough to desired thickness for tarts or pies and bake for 20-25 minutes until golden brown and flaky.