Preheat oven to 400°F
Roast the hazelnuts on a parchment covered cookie sheet for 5 to 7 minutes. Let them cool for 2 - 3 minutes. Carefully place between paper towels and rub off the skin. Transfer the nuts to a food processor and pulse until finely ground.
Preheat oven to 375°F
In in a large bowl combine the finely ground hazelnuts, hazelnut flour, sea salt and coconut sugar. Add the cold butter cubes and working quickly with your hands knead the dough until large crumbs form.
In a a small bowl whisk egg yolk with wine.
Add egg yolk mixture to the dough and continue to mix for about 1 minute.
Turn the dough onto a large piece of plastic wrap and shape into a flat disc.
Refrigerate for at least 1 hour (you can leave it over night or freeze). Remove 30 minutes before rolling out on a slightly floured surface. Roll out the pastry dough about ¼ inch thick and 2 inch larger then your tart pan with removable bottom. Gently press the dough to the bottom and sides and cut off the excess around the edges. With a fork pierce all over.
Line the unbaked tart shell with thin aluminum foil and fill with pie weights or dry beans. Bake for 15 minutes or until edges turn light brown.
Remove the foil with the weights and bake for 10 minutes or until crust turns golden color. Let it cool before removing from tart pan. (you can make the crust a day ahead)