Pastry:Sift flour and salt into a bowl, rub in butter, add egg yolk and lemon juice and mix to a firm dough. Cover and refrigerate 20 minutes. Roll dough out large enough to line a 25cm flan tin, trim the edges. Cover pastry with greaseproof paper and fill with dried beans or rice to hold in shape while cooking. Bake in a moderate oven for 7 minutes, remove paper and beans and bake a further 7 minutes. Set aside until required.
Melt butter in a pan and cook onion and bacon for 2 minutes until tender.
Use commercially prepared short pastry if desired.
(Available at supermarket)