Preheat oven to 350º F/ 180º C.

In a food processor combine butter, sugar, orange or lemon zest and flour. Process for about 1 minute, until the mixture becomes crumbly.

Alternatively use a potato masher in a bowl or just make crumbs with your hands.

Transfer the dough to a 10 inch/ 24 cm tart pan. Press it to the bottom and the sides of the pan. It may still be a bit crumbly but that's ok. If you find it easier, roll the dough and spread the sheet at the bottom and the sides of the pan.

Place a sheet of parchment paper on top of the crust. Spread pie weights or about 1 pound/ 500 g white beans on top of the paper.

Bake for 20 minutes or until the sides of the crust become light-golden.

In a large mixing bowl beat with an electric mixer mascarpone, sugar and vanilla until fluffy. Add the eggs and beat for 15-20 seconds, until just combined. Scrape the sides of the bowl, if needed.

Pour the filling into the crust. Arrange the sliced strawberries on top.

Bake for another 20 minutes or until lightly golden dots start appearing on top of the filling.

Let cool until room temperature and then cover with cling film. Refrigerate for about 4 hours or overnight.