Smoked haddock, tomato and cheese quiche

225g/8oz shortcrust pastry
25g/1oz butter
1 medium onion, peeled and sliced
15g/½oz plain flour
125ml/¼pint milk
salt and pepper
3 eggs, beaten
75g/3oz grated cheese
225g/8oz smoked haddock, cooked and flaked
3 medium tomatoes, chopped

1. Roll out pastry and line a 23cm/9 inch flan dish
2. Melt butter in a saucepan and cook onion until soft
3. Stir in flour and then milk
4. Bring to the boil, stirring continuously
5. Remove sauce from the heat, add seasoning, beaten eggs and half cheese
6. Arrange flaked fish and tomatoes on pastry and pour sauce over
7. Sprinkle with remaining cheese
8. Bake in a fan oven 160ºC, electric oven 180ºC, gas oven mark 4 for 30 - 40 mins until set and golden brown