Tuna pie with potato and sausage

DIRECTIONS

1. For the béchamel sauce:
   Place the butter in a saucepan and heat over low heat. When the butter start to melt, add the flour with a little milk and whisk until the flour is dissolved. Gradually add the rest of the milk, increase to medium heat and stir until a homogeneous and creamy mixture, about 10 minutes.
2. Turn off the heat and season with a little salt, pepper and nutmeg. Mix the seasonings in the sauce and let cool.
3. Drain and shred the tuna with a fork; set aside.
4. Peel, wash the potatoes and cut into small cubes. Season with salt and fry in very hot oil. When the potatoes are fried, place them in a dish with absorbent paper.
5. Place the olive oil, chopped onion and the peeled tomatoes cut into small pieces in a saucepan and cook over low heat until the tomato start to break down, stirring occasionally. Add the tuna, chopped coriander, béchamel sauce and the fries. Stir and cook for about 2 to 3 minutes, stirring occasionally. Turn off the heat and let stand about 5 minutes.
6. Preheat the oven to 180ºC (350ºF).
7. Grease a pie pan (24 centimeters (9 1/2 inches)) with butter, line with the pastry and prick the bottom with a fork. Pour the tuna and potato mixture over the pastry, garnish with Portuguese sausage slices and sprinkle with grated cheese. Bake until golden, about 30 minutes.
8. Turn off the oven and serve.