1. Sift the flour and sugar into a medium sized bowl. Mix in the lemon zest and salt with a whisk. Using a pastry cutter or two knives, cut in the butter until the mixture becomes course crumbs. Add in the egg, and mix with your fingertips until combined. Form into a ball. The dough will be crumbly, but if you can’t form it into a ball, add about up to 2 tablespoons of cold water, 1 teaspoon at a time. The more water you add, the less crumbly and less “shortbread” like your crust will become. Cover with plastic wrap and let chill for up to 30 minutes.

2. Preheat oven to 375F. Mix the pitted cherries with the lemon juice, flour, sugar and set aside.

3. Roll out the crust into a round, a bit more than a 1/4 inch thick on a lightly floured sheet of parchment. This dough is really tricky to work with as it likes to just crumble apart, so the parchment will help you move it to the baking sheet.

4. Pile the cherry mixture into the center of the dough, and then starting from one side, carefully fold up the dough around the cherries, and then move about 20 degrees and fold the next section up. Repeat until you’ve folded all the sides up. You are likely to have a lot of cracks. Pinch them together as best as you can… but don’t worry about them too much… this is a rustic tart. Then, carefully cut vents in the top of the tart and sprinkle the top with sugar.

5. Transfer the whole piece of parchment to a baking sheet, and bake for 25 to 35 minutes, or until golden brown and you start to see juice bubbling out. Let cool for about 10 minutes before slicing.