Butter Tarts

Sour Cream Pastry - In a bowl, whisk flour with salt; using a pastry blender, cut in butter and lard until in fine crumbs with a few larger pieces - Whisk water with sour cream and drizzle over flour mixture, tossing briskly with fork and adding more water if necessary to form ragged dough - Press into disc; wrap and refrigerate until chilled (about 30 minutes) - On a lightly floured surface, roll out pastry to generous 1/8" thickness; using 4" round cutter, cut out 12 circles, re-rolling and cutting scraps - Fit into 12 muffin cups and refrigerate for 30 minutes Butter Tart Filling - Whisk together brown sugar, maple syrup, butter, eggs, vinegar and salt - Divide walnuts, currants and raisins among pastry shells; spoon scant 1/4 cup filling into each shell - Bake at 350°F until filling is set and pastry is golden (about 20 to 25 minutes) - Run thin knife around edges to release tarts; let cool for 20 minutes