- In a bowl, whisk flour, powdered sugar, and salt. Cut in butter until it resembles coarse crumbs. 
- Add egg yolk and cold water. Mix until the dough comes together. Flatten into a disc and chill for 30 mins. 
- Roll out dough and press into a 9-inch tart pan. Trim edges and freeze for 15 minutes. 
- Preheat oven to 375°F (190°C). Line the crust with parchment and fill with weights. Bake 15 minutes, remove weights, and bake 5 more until golden. Cool completely. 
- To make the custard, heat milk in a saucepan until steaming. In a bowl, whisk sugar, cornstarch, salt, and egg yolks. 
- Slowly whisk hot milk into yolk mixture, then return all to the saucepan. Cook over medium heat, whisking constantly until thickened. 
- Remove from heat and stir in butter and vanilla. Transfer to a bowl, press plastic wrap on the surface, and chill. 
- Spread cooled custard in the tart shell. Arrange strawberries on top. Chill for at least 1 hour before serving. Dust with powdered sugar if you like.