Place the orange zest, juice and lemon juice in a measuring jug. Make up to 3/4 pint (15fl oz) with the extra orange juice. Add the Cloves and sugar and bring to the boil. Remove from the heat, cover and set aside for approximately half an hour.
Brush the gammon steaks with oil, sprinkle over the Pepper and grill for about 5 minutes on each side. Keep warm.
Remove the Cloves from the orange juice. Add the cornflour mixture and reheat, stirring, until the sauce boils and thickens. Stir in the butter and pour over the gammon to serve.