Blitz your pastry ingredients in a food processor (egg and water at the end only) to form a dough, then leave to chill for about 30 minutes in the fridge.
Heat the oven to 180°C.
Roll out the chilled dough and line the pastry tin. Prick the base with a fork and blind bake using baking beans for 10-12 minutes. Remove the beans and bake for a further 5-6 minutes.
For the filling, mix together everything except the Västerbotten cheese.
Scatter the cheese on the base of the pastry, evenly all over – then pour over the egg mixture.
Return it to the oven for about 15-20 minutes. It’ll puff up quite a bit towards the end, but will turn golden on top. It’s done when it is ‘set’ so do keep an eye on it.
Leave it to cool before slicing. Serve cold or lukewarm.Västerbottenpaj goes well with romsås, a caviar sauce. Alternatively, if you can get real bleak roe (Löjrom), serve the tart with a spoonful of this, some crème fraîche and finely chopped red onion.
Romsås Caivar Sauce:
In a bowl, mix together 3 large tbsp. crème fraiche and one jar of red lumpfish roe (80g). Leave to set in the fridge, then stir again just before serving.