For the gluten-free and vegan quiche pastry
Put the flour and salt into a mixing bowl and rub in the margarine until the mixture resembles breadcrumbs.
Mix in just enough water to form a dough.
Shape into a ball and wrap in cling film. Chill for 30 minutes.
Heat the oven to 200°C (180°C fan). Grease a 23cm flan dish or tin.
Roll out the pastry on a lightly floured surface into a round to fit the tin.
Line the base and sides of the tin with the pastry.
Prick the pastry all over with a fork, line the pastry case with non-stick baking paper and fill with rice or dried beans.
Bake for 10 minutes. Remove the paper and beans and bake for a further 10 minutes until golden.
Reduce the oven temperature to 180°C (160° fan).
For the gluten-free and vegan quiche filling
Heat the oil in a pan and cook the potatoes for 5 minutes until lightly browned on both sides.
Remove from the pan. Add the Brussels sprouts and cook for 5 minutes.
Remove from the heat and set aside to cool.
Arrange the potatoes and Brussels sprouts in the pastry case.
Combine the chickpea flour, nutritional yeast, salt, nutmeg, and turmeric. Add 240ml water and whisk until smooth.
Heat the remaining water in a large pan and bring to a simmer.
Whisk in the chickpea mixture and bring back to a simmer.
Cook over a low heat for 5-8 minutes, stirring constantly, until thickened.
Pour over the vegetables and sprinkle with cheese.
Bake for about 25 minutes until golden. Serve the gluten-free and vegan quiche warm.