Add the butter, flour and sugar to a bowl and combine using a pastry blender or a butter knife until the flour is just combined and there are visible lumps of butter – avoid using your hands.

In a separate small bowl, lightly whisk together the egg, apple cider vinegar and 80ml ice-cold water to incorporate. Make a well in the centre of the flour mixture and pour in the wet ingredients.

Using two large forks, gently toss the wet ingredients into the dry until a rough dough forms.

Turn the dough out onto a sheet of greaseproof paper, wrap, and chill for at least 30 minutes before rolling out.

While the pastry is chilling, toss the rhubarb, strawberries, caster sugar, flour and vanilla bean seeds in a medium-sized bowl, then set aside.

On a generously floured work surface, roll out the dough into a large round about 5mm thick and then transfer the dough onto a baking tray lined with greaseproof paper.

Spread the pastry with ricotta cheese leaving roughly 10cm around the edges free. Pile prepared rhubarb and strawberries onto the ricotta. Fold the edges of the pastry inward, over the rhubarb, leaving the centre of the rhubarb exposed, and creating a barrier so the juice cannot escape as the tart cooks.

Brush the outside edges of the pastry with beaten egg yolk. Bake the tart in a hot oven, 210C/190C fan/gas mark 5 for 30-35 minutes or until the sugar and juices bubble in the center of the tarts and the pastry is golden brown. Remove the tart from the oven and allow to cool slightly before enjoying with a dollop of whipped cream or cold vanilla ice-cream.