In a large bowl, cream together butter, brown sugar, egg yolk, and vanilla.
In a separate bowl, mix together flour, salt, and baking soda. Add to wet ingredients and mix until a smooth dough forms. (The dough may seem a bit dry at first, just keep mixing until everything is moistened and holds together nicely.)
Roll the dough into 1” balls.
Place 2 tablespoon white sugar into a small bowl and coat each ball of dough in sugar. Place the sugared dough balls 1” apart on an un-greased baking sheet.
Press your thumb into each ball to create an indent in the center of the cookies.
Bake for 10 minutes.
Remove the cookies from the oven and, while the cookies are still hot, top each cookie with approximately 1 teaspoon of mincemeat.
After the cookies have had 5-10 minutes to cool on the baking sheet, remove them from the baking sheet to cool completely on a wire rack. Once cool, store in an airtight container.