- Portion size 10 servings
In large bowl, stir together flour, ground hazelnuts and salt. With pastry blender or 2 knives, cut in butter and shortening until mixture resembles coarse crumbs. In liquid measure, whisk egg yolk with vinegar; add enough ice water to make 1/3 cup (75 mL). Gradually sprinkle over flour mixture, stirring briskly with fork until pastry holds together. Press into disc; wrap in plastic wrap. Refrigerate for at least 1 hour or until chilled. (Make-ahead: Refrigerate for up to 3 days.)
Spread hazelnuts and pine nuts on separate baking sheets; toast in 350°F (180°C) oven for about 8 minutes or until lightly golden. Transfer hazelnuts to tea towel; rub off as much of the skins as possible; chop coarsely. Let cool.
On lightly floured surface, roll out pastry to 1/4-inch (5 mm) thickness. Place in 9-inch (23 cm) round or square tart pan with removable bottom, trimming to fit. Line with foil; fill evenly with pie weights or dried beans. Bake in bottom third of 375°F (190°C) oven for 15 minutes; remove weights and foil. Bake for 10 to 12 minutes longer or until pastry just starts to turn golden. Let cool. Reduce heat to 350°F (180°C).
Scatter pine nuts and half of the hazelnuts evenly into tart shell.
Meanwhile, in bowl, vigorously whisk together sugar, corn syrup, butter, eggs, vanilla and vinegar; pour over nuts, smoothing top.
Scatter remaining hazelnuts around edge of tart. Place tart on baking sheet. Bake in bottom third of 350°F (180°C) oven for about 35 minutes or until just set and centre is jiggly. Let cool on rack.