Use a large bowl to combine and whisk the flour and salt. Work in butter and/or lard using a pastry cutter.
Whisk the egg yolk and vinegar and then add enough ice water to make 1/3 cup (75 mL). Sprinkle this over the flour mixture and stir briskly using a table fork until the pastry holds together.
Press and form the dough into a disc and then wrap it in plastic wrap and place in the refrigerator to chill for one hour.
For the butter tart filling
Combine all of the filling ingredients into a large bowl and whisk together until thoroughly combined.
To finish the butter tart recipe
On a lightly floured surface, roll the dough out to 1/8 inch (3 mm) thickness.
Use a 4-inch round cookie cutter (or the rim of a drinking glass) and cut out 12 pastry forms. Re-roll the scraps if necessary.
Place the forms in a 2-3/4- x 1-1/4-inch (7 x 3 cm) muffin pan and evenly divide the optional raisins among them. Fill each pastry shell 3/4 to the top with the butter tart filling.
Bake in the lower third of your oven for about 12 minutes or until the pastry is golden brown and the butter tart filling is puffed and bubbly. Remove from oven and allow to rest for a minute or two.
Use a metal spatula to carefully loosen the sides of the butter tarts and transfer them to a metal cooling rack.
Notes
To make the filling for these butter tarts more firm, make the following adjustments: