peppercorns and bay leaf into a large pan and add enough water to cover the ingredients.
Bring the mixture slowly to the boil
then reduce the heat and simmer for 25–30 minutes
or until the chicken is cooked through.
Remove the chicken from the pan and set aside. Keep warm. Strain the cooking liquid and reserve 450ml/16fl oz of it. Set aside.
Heat half of the butter in a large separate pan and add the flour. Stir over a low heat until the mixture forms a smooth paste that leaves the sides and base of the pan cleanly. Gradually add the reserved cooking liquid
stirring well after each addition
to make a sauce. Season
to taste
with salt and freshly ground black pepper.
Add the broccoli and water chestnuts to the sauce.
In a bowl
mix the egg yolk with the cream and slowly add this mixture to the sauce. Add a squeeze of lemon juice and stir to combine.
Cut the cooked chicken into bite-sized pieces and return to the sauce. Stir well.
In a separate pan
heat the remaining butter and fry the remaining thinly sliced onion until soft and golden-brown.
