140 g blackberries
225 g blueberries
4 plums, stoned and chopped
3 tbsp granulated sugar
2 ¼ tbsp cornflour
zest 1 orange
custard or double cream, to serve (optional)
For the pastry
200 g butter in a block, frozen
300 g plain flour plus extra for dusting
5 tbsp granulated sugar plus a little extra for sprinkling
1 egg white
- The morning before you want to make the tart, remember to put the butter in the freezer – try wrapping it in foil first (it will keep it colder when you hold it to grate later).
- To make the pastry, mix the flour in a big bowl with a good pinch of salt and 2 tbsp of the sugar. Using a coarse cheese grater, grate in the butter, trying to hold it as little as possible so that it doesn’t warm up too much, and stirring it in with a cutlery knife as you go. When all the butter is in, give it a final good stir with the knife to make sure all strands of butter are coated in the flour, then quickly stir in 150-175ml of very cold water. Lightly bring the pastry together with your hands, wrap in cling film and chill for 30 mins.
- Layer all the fruit in another bowl, sprinkling over the sugar and cornflour as you go. Add the orange zest and give everything a light mix. Set aside until your pastry is ready.
- Heat oven to 200C/180C fan with a baking sheet in it. Lightly dust another baking sheet with flour and roll out the pastry onto it in a rough circle until the pastry is about 0.5cm thick. If you want, use a small, sharp knife to cut a pattern around the edge of the pastry.
- Give the fruit another mix, then pile into the middle of the pastry, leaving a 7cm border of clear pastry all around the edge. Fold the pastry border up and over the fruit filling, pinching bits together to keep it neat and in place. Whisk the egg white until very frothy. Using a pastry brush, brush the froth all over the pastry. Dredge over the remaining granulated sugar, and sprinkle a little more over the fruit. Lift onto the heated sheet and bake for 35 mins until the pastry is golden brown and crispy. Serve straight from the oven with lashings of custard or, if you’re feeling really wicked, some Cornish clotted cream.