Rinse chicken fillets in warm water and pat dry. Rinse and dry tarragon before chopping leaves finely. Rub pepper into chicken fillets, sprinkle with chopped tarragon and lemon juice, cover and marinate for 10 minutes.

Peel and chop shallots.

Rinse and pat dry prawns, removing black vein if necessary.

Take chicken out of marinade and dry thoroughly. Put marinade aside. Cut chicken into strips 1 cm (1/2 in) wide.

Heat butter in large heavy-bottomed pan until foamy, then fry chicken strips for 4 minutes, turning frequently so that they brown evenly. Add shallots and fry for 1 minute more.

Add prawns and continue to fry, turning constantly, for another minute.

Beat cream with egg yolk, stir into fricassee and heat through gently, without allowing mixture to boil. Pour in champagne and reheat, again not allowing fricassee to boil.

Season well with salt, cayenne pepper and marinade.

Serve with green ribbon noodles or potato croquettes and buttered peas.