Chop 1 piece of stem ginger. Place 1 tbsp of the syrup from the jar in the bottom of a lightly greased 900ml (2pt) pudding basin.
Finely grate the zest from 1 orange and set aside. Cut away the peel and slice the orange. Arrange the orange slices in the pudding basin.
Beat 125g (4oz) butter and 125g (4oz) sugar together until pale and fluffy. Addtwo eggs one at a time, beating well after each addition. Add 1 tbsp of 125g (4oz) flour with the second egg to prevent the mixture from curdling.
Add the orange zest and the chopped ginger to the bowl, then sift in the remaining flour and 2 tsp baking powder. Add 1 tbsp warm, not hot water and carefully fold the mixture together until just combined. Spoon into the prepared pudding basin and level the top.
Cover with a sheet of baking parchment and a sheet of foil and tie to secure. Steam for 1½ hours. To test the pudding is cooked a skewer inserted into the centre should come out clean.
Allow the pudding to cool in the basin for at least 5 minutes before turning out onto a warm serving plate.
Meanwhile make the orange foam sauce
Prepare the sauce just before ready to serve. Beat the 50g (2oz)each butter and sugar together in a saucepan until combined.
Finely grate the zest from the oranges and beat into the butter and sugar mixture. Then beat in 2 eggs yolks, followed by 2 tbsp flour.
Squeeze the juice from 2 oranges and make up to 300ml (½pt) with a little water if required. Beat into the butter mixture, do not worry that the mixture looks curdled at this point. Heat gently stirring until the mixture thickens.
Whisk 2 egg whites until standing in soft peaks. Slowly add the hot orange mixture to the egg whites folding in to combine. Serve with the orange and stem ginger pudding.
For more details of how to steam a puddingNutrition information is calculated usingan online nutrition database - is approximate and is meant as a guideline only.