Preheat the oven to 220°C. Sift the flour and baking powder into a bowl, then rub in 2½ tablespoons butter. Add 4 tablespoons sour cream and mix to a soft dough.
Roll out the dough on a floured surface into a circle about 28cm in diameter, and fit into a 25cm loose-based flan or quiche tin. Trim the edge, prick the base, line with greaseproof paper and fill with baking beans or small balls of scrunched-up cooking foil. Bake blind for 10 minutes.
Meanwhile, halve, peel and thinly slice the onions, then strip the thyme leaves from the stems and chop finely. Heat the oil in a large frying pan, add the onions and thyme and fry over moderate heat until the onions are soft and golden.
Melt the remaining butter in another frying pan. Clean and halve the mushrooms and fry until lightly browned, then stir in the rest of the sour cream and keep warm.
Remove the paper and baking beans or foil from the flan case, then return to the oven for a few minutes until the pastry is golden.
Snip the chives. Crumble the feta cheese into the onions. Heat for 1minute then season to taste with pepper. Spoon the mixture into the flan case and spoon the mushrooms over the top. Sprinkle with chives and more pepper and serve.
NUTRIENTS PER SERVING:
good source of vitamins A, B group, E and folate, and calcium.
You can add extra colour to this flan by using red onions; you can also use a variety of mushrooms, rather than just the one.