Grilled Onion and Potato Slices

For 4 people you need

2 good sized onions
4 large potatoes
seasoning

 For the sauce

1 oz. margarine
1 oz. flour
1/2 pint milk seasoning.
2-3 oz. grated Cheddar cheese

1. Peel both the onions and potatoes.
2. Slice onions thinly, and potatoes thickly, and cook in boiling salted water until just tender, then strain.
3. Meanwhile make the sauce: Heat the margarine in a pan, stir in the flour and cook for several minutes, then gradually stir in the milk, bring to the boil and cook stirring well until thickened and smooth, season.
4. Arrange vegetables in a dish with the sauce, top with grated cheese and cook under grill until crisp and brown.