To make pastry, sift flour and salt into a large bowl.
Using a pastry blender or 2 knives, cut in butter or margarine until evenly distributed and mixture resembles breadcrumbs.
Lightly mix in egg and enough ice water to make a dough.
Press into a ball and wrap in foil or plastic wrap.
Refrigerate 30 minutes.
To make filling, trim, wash and slice leeks.
Dice bacon.
Heat oil in a large skillet; add bacon and cook until lightly browned.
Add leeks.
Sprinkle with salt, pepper and curry powder.
Cook over medium heat 10 minutes.
Preheat oven to 400°F (205°C).
On a floured surface, roll out dough to fit a 9-inch (23-cm) flan tin.
Place dough in tin without stretching.
Arrange pork sausage slices over pastry shell.
Spread with leek filling.
In a medium bowl, beat eggs, sour cream and salt and pepper to taste.
Pour over filling.
Bake 50 to 60 minutes or until filling is firm.