To make the pastry: Whisk flour and salt together in a large bowl. Cut lard into flour mixture with a pastry blender until crumbly. Make a well in the center; place beaten egg into the well. Pour in ice-cold water and vinegar; stir with a wooden spoon until dough comes together. Divide dough into 2 balls; wrap each in waxed paper and chill in the refrigerator for 1 hour.

Preheat the oven to 350 degrees F (175 degrees C).

To make the filling: Beat brown sugar and melted butter together in a large bowl with an electric mixer until smooth. Beat in eggs one at a time, mixing well after each addition. Stir in raisins and vanilla until incorporated. Set aside.

Roll out 1 ball of chilled dough on a lightly floured surface to 1/8-inch thickness; reserve remaining dough for another use. Using a round biscuit cutter, cut dough into circles large enough to fit into the bottom and partially up the sides of the wells of a muffin tin. Press dough circles lightly into the muffin tin to form tart shells. Fill each shell 3/4 full with raisin filling.

Bake in the preheated oven until filling is bubbly and pastry is lightly browned, about 20 minutes.