1. Preheat your oven to 190°C (375°F).

2. In a large mixing bowl, combine the flour and salt. Add the cold butter and use a pastry blender or your fingertips to cut it in until the mixture resembles coarse breadcrumbs.

3. Gradually pour in the ice-cold water while mixing, just until the dough comes together. Wrap it in plastic wrap and chill in the refrigerator for at least 30 minutes.

4. On a lightly floured surface, roll out the dough to about 3 mm (1/8 inch) thick. Carefully transfer it to a 23x33 cm (9x13 inch) baking dish.

5. In another bowl, whisk together the heavy cream, eggs, milk, melted butter, curry powder, and tomato purée. Season with salt and pepper to taste.

6. Arrange the diced salmon and shrimp evenly over the pastry, leaving a 2.5 cm (1 inch) border around the edges. Pour the cream mixture over the seafood.

7. Fold the edges of the pastry up and over the filling, pressing lightly to seal.

8. Brush the top of the pastry with a little extra heavy cream and sprinkle with chopped fresh dill, if desired.

9. Bake in the preheated oven for 35 to 40 minutes, or until the pastry is golden brown.

10. Remove from the oven and let it rest for a few minutes before slicing and serving.