I used red onion chopped instead of yellow onions sliced, but this just adds to the variation. I also was asked by weezl, if I would replace 50g of the flour for the pastry with instant oats cereal to add calcium and B12 to the pastry. It was successful. So until it gets updated with final version on her site. I used 60g self raising flour and 50g of instant oat cereal (like ready brek type cereal) The pastry is like a savoury biscuit/scone type base, and most yummy. This tart would suit many fillings. I served with salad and potato salad and I also had it with cooked vegetables. All gone now and yummy it was too. Will be making it again soon, will try yellow onions next time.