- Heat oven to 200°C (180°C fan). Put the butter or margarine in a bowl with the dry ingredients and rub together.
- Add the beaten egg, and mix until the mixture begins to clump together. Gather into a ball with your hands, and knead it well until smooth and free from cracks.
- Flatten the dough into a block about 2cm thick. If not using immediately refrigerate until using.
- Roll it out until it is about 1cm thick and use it to line a 25cm tart tin or dish. Refrigerate until firm — about 30 minutes and then line the tin with baking parchment and baking beads and blind bake the case until the base is light golden – this should take 15 minutes with the beads in and a further 5 once you have removed them.
- Leave to cool in the tin on a wire rack.
- Remove the woody ends from the asparagus and wash. Steam or boil them until soft — only a few minutes then drain on kitchen paper and reserve.
- In a frying pan, with 60ml of sunflower oil, fry the onion until golden. Add the sugar, stir well and continue cooking until the onions are caramelized.
- Then spread the caramelised onions all over the base and arrange the asparagus into a nice pattern. Cook again for 6 - 8 minutes at 200°C. Add salt and pepper.
This is perfect when you cannot face another plate of meat and potatoes!