White Fish Sauce.

Six tablespoons flour (flat); 3 tablespoons butter; 1 cup fish sauce; slice of onion; 1/2 cup milk; salt and pepper to taste; lemon juice.

Boil stock, milk and onion for five minutes. Melt butter in saucepan. Add flour and stir over fire for a few minutes (do not brown). Gradually add stock and milk and simmer for 10 minutes, stirring constantly. Strain, add seasoning and a few drops lemon juice.