To make the pastry, sift the flours and a pinch of salt into a mixing bowl, adding any bran remaining in the sieve. Rub in the fat spread until the mixture resembles fine breadcrumbs, then mix in enough of the egg to form a slightly soft, but not sticky, dough.
Knead the dough on a lightly floured work surface for a few seconds until it is smooth, then roll it out into a 30 cm (12 in) round. Line a 25 cm (10 in) flan tin with the dough, trim the edge and place in the refrigerator for at least 30 minutes to chill.
To make the filling, put the oil, onions, brown sugar and a pinch of salt into a nonstick frying pan, mix them together and fry over a fairly low heat for 25-30 minutes, stirring frequently, until the onions are softened and lightly caramelised. Remove from the heat and set aside.
Heat the oven to 220°C (425°F, gas mark 7) and put a baking sheet in to warm.
Break the eggs into a mixing bowl, add the milk and pepper to taste and whisk well. Then stir in the watercress and half the Parmesan cheese.
Spoon the cooled onions into the pastry case, spreading them out evenly, then pour in the watercress mixture and sprinkle the diced pepper and remaining Parmesan over the top.
Place the quiche on the hot baking sheet and cook for 35-40 minutes until the filling is set and the topping is lightly browned. Serve it hot or at room temperature.
Variation: for added flavour, you can sprinkle 15 g (½ oz) of pine nuts over of the quiche before baking it, but they will add 2 g of fat per serving. Cover the quiche loosely with foil if the pine nuts start to brown before the filling is set.
Parmesan cheese is not truly vegetarian, as it contains animal rennet. To make this dish 100% vegetarian, omit the cheese or find a suitable vegetarian substitute made without animal rennet. In supermarkets look for the 'parmesan style hard cheeses' which are suitable for vegetarians.
I made this dairy-free by replacing the milk with a mixture of water and oil, and using parmesan-style vegan cheese. I must point out that I'm not a fan of vegan cheeses, but this one was soya-free and not as awful as many others I've tried. The quiche came out really tasty despite the cheese, even my carnivorous friends enjoyed it. With some real (i.e. dairy) hard cheese I'm sure this would be amazing! - 03 Jul 2012