Blend the flour, icing sugar, and 55g of butter in a food processor until crumbly.
Add egg yolk, orange zest, and mint, then blend with water until the dough forms.
Roll the dough to the size of a small frying pan on a floured surface.
Fry the pastry in a pan over medium heat for 2-3 minutes per side until golden.
Arrange plum slices, 25g of butter pieces, and caster sugar on the pastry.
Fry for 3-4 minutes until the sugar and butter melt into a gooey topping.
Whisk the double cream with icing sugar and vanilla seeds.
Plate the tart and serve with a dollop of vanilla cream.