In a large bowl, combine the flour, sugar, and salt. Cut in the butter using a dough blade, your fingers, or forks until the mixture becomes coarse with no pieces larger than a pea.
Mix in the egg yolk and slowly add water until until the dough comes together. Form the dough into a disc, wrap in plastic, and refrigerate for 1 hour.
Hull the strawberries and slice in half (or quarters for the larger strawberries). Place in a large bowl and toss with the sugar, cornstarch, lemon juice, and pinch salt.
Preheat oven to 400˚F. Line a large or circular baking sheet with parchment.
On a lightly floured surface, roll the chilled dough into a thin circle about 12 inches wide. Transfer to the prepared baking sheet.
Spread the Nutella across the middle of the prepared dough, leaving a 2 inch border around the edges. Use a slotted spoon to remove the strawberries from the bowl and arrange over the Nutella.
Fold the clean dough edges over the filling around the circle, leaving the center open.
Beat the egg yolk with the 1 teaspoon water. Brush the egg wash along the exposed edges of dough. Sprinkle with the raw sugar. Bake in preheated oven until the crust is golden, about 30 minutes.
Allow to rest for 5-10 minutes before serving. Drizzle with additional Nutella if desired.