Shrimp sauce

• 575 ml (1 pint) fresh shrimps
• 1 onion, sliced
• 25

Shell the shrimps and put the shells in a saucepan with the water and the onion. Bring to the boil and simmer for 30 minutes. Strain the liquid.

Melt the butter in a small saucepan, stir in the flour, let it cook for 1 minute, then add the milk gradually, stirring after each addition until you have a smooth sauce. Now add 150 ml (¼ pint) of the shell cooking liquid. Season with cayenne