Sour cherries: In a medium bowl add the pitted sour cherries, 50g light brown sugar and 1 tsp of ground cinnamon. Mix and set aside for half an hour.
Sweet pastry: In a medium bowl, add the flour and butter. Work it with your fingertips until it is soft and turns into fine crumbs. Alternatively, add both the flour and butter to a food processor and mix for 30 seconds to create a fine crumb. Add the caster sugar and a pinch of salt, mix well then add the eggs and mix again until a dough forms. (If it isn’t coming together, add a little cold water – no more than 1-2 tbsp.)
Roll the dough into a ball and cut 1/3 off, for the tart lattice top.
Reform both pieces into balls, flatten slightly, wrap in cling film and then put in the freezer for 15 minutes to rest.
Ricotta filling: In a medium bowl, mix together the ricotta, sugar, vanilla and eggs. Once mixed place in the refrigerator until needed.
Sour cherries: In a shallow pan or frying pan, bring the sour cherry mix to the boil and reduce the liquid until it almost disappears. If a little liquid remains it is not a problem. This should take no more than 5-6 minutes. Then set aside to cool.
Tart base: To prepare the base, remove the larger pastry dough you made earlier from the refrigerator.Dust your work surface with flour and gently roll out the dough until it is about 5 mm (1/8 inch) thick and 24-25 cm in diameter.Carefully wrap the dough around the rolling pin and place it into a 22 cm x 4 cm tart tin.Gently press the dough into the corners and up the sides. There should only be a little overhang on the edges. Leave this hanging for now and place it in the freezer for 10 minutes or the fridge for 30 minutes to rest again. This will help to avoid the dough shrinking when baking. Preheat the oven to 160°C fan / 350°F / Gas 4.
Remove the smaller piece of dough from the fridge and roll it out until it is about 5 mm (1/8 inch) thick and 23 cm in diameter. Then cut long 1 cm wide strips for the lattice. You will need 10 strips in all, long enough to cross the tart across the top. It may be necessary to repeat the rolling process with any scraps you have leftover.
Assembly: Remove the tart base from the fridge or freezer and, using a sharp knife, gently cut around the top to remove the excess dough.Fill the tart with the ricotta filling and level flat with a spatula or spoon.Then spoon over the sour cherry mix evenly across the top of the surface. Lattice: 1. Lay 5 pastry strips across the top of the tart filling, then fold back the 2nd and 4th strip to the middle. Lay a new strip across the middle and fold back the bottom strips. 2. Fold back the 1st, 3rd and 5th strip on the bottom and lay another new strip across. Fold back the bottom strips.
3. Fold back the 2nd and 4th stripes again and lay another new strip across returning the bottom stripes back after.
4. Repeat this process with the opposite side until finally, you have a nice lattice pattern on the top.Lastly, cut the ends of the strips to fit inside the tart shell and then brush the top with egg wash. Baking: Place the tart on the middle shelf of the oven and bake for 30-35 minutes until golden brown.