- 450ml/3/4pt milk
- 1 bay leaf
- 10 whole black peppercorns
- 1 slice onion, about 1cm/1⁄2in thick
- 50g/2oz butter
- 25g/1oz plain flour
- salt and freshly ground black pepper
- Put the milk in a heavy saucepan over a low heat, and add the bay leaf, peppercorns and onion. Cook for about 5 minutes, letting it come slowly to simmering point. Remove the pan from the heat, and strain the milk into a jug, discarding the flavourings.
- Melt the butter gently in a separate pan. As soon as the butter melts, add the flour and, over a medium heat, stir quite vigorously using a wooden spoon to make a smooth paste, or roux.
- Add the milk a little at a time, stirring vigorously between each addition. When about half the milk is in, switch to a whisk and start adding more milk at a time, whisking briskly, until all the milk has been added.
- Reduce the heat to low, and let the sauce simmer gently for 5 minutes, whisking occasionally. Season with salt and pepper.