1. If using ready-made pastry jump to stage 4. If making from scratch, read on… For the pastry, sift flour and salt into a bowl, adding any bran left in the sieve. Rub in the margarine with your fingers until the mixture resembles fine breadcrumbs. Mix in walnuts, then add enough cold water to form a dough.
2. Alternatively, place all pastry ingredients into a food processor and give it a very quick whizz.
3.Turn out dough onto a lightly floured work surface and knead until smooth and elastic. Wrap in plastic and chill for 30 minutes. Preheat the oven to 200ºC400ºF/Gas Mark 6.
4. For the filling, heat oil in a large heavy based frying pan. Sweat onions over a low heat for 20 minutes until very soft and translucent, stirring often. Stir in thyme, sugar and seasoning and cook for a further 5 minutes until caramelized. Set aside and leave to cool slightly.
5. Blend silken tofu, vegan cream cheese, Dijon mustard and seasoning in a food processor or liquidizer until smooth and creamy.
6. Lightly grease a fluted 23cm/9in loose-bottomed quiche tin.
7. Roll out pastry on a lightly floured work surface, then gently lift it using a rolling pin. Don’t worry if it breaks up. If using a ready-rolled sheet, no need to do any rolling!
8. Press pastry into tin with your finger tips and trim top. Use extra bits to mend any holes.
9. Prick pastry base with fork, line with greaseproof paper and baking beans and bake blind for 10 minutes until lightly golden. (You can use any old beans to weigh down the baking paper – baking blind is just a method to part-cook pastry so it doesn’t over-brown but also doesn’t go soggy when the filling is added).
10. Remove paper and beans, then spoon over onions.
11. Spoon over tofu mixture and smooth with a knife.
12. Bake for 20-30 minutes until golden and set. Test after this time and return to oven if it needs more baking.
13. Make your salad while it’s cooking, then serve.