Don’t be intimidated by this elegant tart. It’s actually quite simple and couldn’t be more delicious. A toasty buttery crust is filled with a sweet vanilla cream, topped with fresh strawberries and a dusting of sugar before serving.
Make the crust: Whisk the vegetable oil, egg yolk, milk and vinegar in a medium bowl. Pulse the flour, baking powder, sugar and salt in a food processor to combine; add the butter and pulse until the mixture looks like coarse meal. Add the milk mixture and pulse once or twice, just to moisten the flour.
Pat the dough onto the bottom and up the sides of a 9-inch round tart pan with a removable bottom. Cover with plastic wrap and refrigerate until firm, at least 30 minutes. Trim the edges, if necessary.
Preheat the oven to 350 ̊ F. Pierce the dough all over with a fork. Line with foil and fill with pie weights or dried beans. Place on a baking sheet and bake 15 minutes. Remove the foil and weights; bake until golden, 10 to 15 more minutes. Beat the whole egg and the water; brush on the crust and bake 5 more minutes. Transfer to a rack and let cool completely.
Meanwhile, make the filling: Sprinkle the gelatin over the cold water in a bowl; let soften 5 minutes. Put the granulated sugar and vanilla seeds in a saucepan; rub together with your fingers. Whisk in 1 cup light cream over medium heat to dissolve the sugar. Bring to a boil, then remove from the heat and whisk in the gelatin mixture. Transfer to a bowl and set in a larger bowl of ice water; stir with a rubber spatula until thickened. Stir in the remaining 1/4 cup light cream. Pour into the cooled tart shell and refrigerate until set, 1 hour.
Before serving, top the tart with the strawberries. Dust with confectioners’ sugar.