1.Process flours and butter until combined. Add sour cream, process until mixture just comes together. Turn onto a board, shape into a flat disc. Cover with plastic wrap; refrigerate 30 minutes or freeze 15 minutes.
2.Meanwhile, preheat the oven to 180°C (160°C fan-forced). Roll pastry between two sheets of baking paper until large enough to line a 25cm loose-based flan tin (3.5cm deep). Remove baking paper, ease pastry into side; trim pastry. Place tin on an oven tray. Line pastry with baking paper, fill with pastry weights, dried beans or rice. Bake for 15 minutes. Remove paper and weights; bake for a further 10 minutes or until browned lightly. Cool 10 minutes.
3.Lightly beat eggs and milk in a medium bowl; season well with salt and freshly ground black pepper.
4.Sprinkle pastry case with dill. Place small spoonfuls of ricotta and slices of trout into pastry case; sprinkle with onion and capers. Pour egg mixture slowly into case. Place tomatoes on tray next to flan tin; sprinkle with salt and pepper.
5.Bake quiche and tomatoes for about 10 minutes or until tomatoes are just softened. Transfer tomatoes to a plate. Bake quiche for a further 20 minutes or until just set in the centre.
6.Serve quiche with tomatoes and rocket.
You can use reduced-fat dairy spread and light sour cream in the pastry if you prefer, however it will change the flavour and texture. To make a sweet version of this pastry, add ¼ cup (40g) pure icing sugar to the flour and the seeds scraped from 1 vanilla bean.