Quiche lorraine

For the shortcrust pastry:

175g (6oz) plain white flour

75g (3oz) butter

1 egg yolk, preferably free-range

2 tsp cold water, approx

For the filling:

1 tbsp olive oil

175g 6oz) streaky bacon cut into 1cm (1/2 inch) lardons

100g (4oz) chopped onions

3 eggs and 2 egg yolks

300ml (½ pint) double cream

1 scant tbsp chopped parsley

1 scant tbsp chopped chives

110g (4oz) Gruyère cheese, grated

salt and freshly ground black pepper