Orange pudding

Melt the butter in a saucepan over low heat, add flour and stir until smooth. Cook for one minute. Do not let mixture brown.
Remove saucepan from stove and beat in egg yolks, orange peel and strained orange juice and lemon juice, a little at a time.
Return to stove and stir over low heat to make a smooth, thick sauce.
Simmer gently for two minutes, stirring continuously.
Remove from stove, stir in castor sugar and cool slightly.
Whisk egg whites until foamy, add cream of tartar and continue whisking until the egg whites hold their shape.
Carefully fold orange sauce into whisked egg whites, using a slotted metal spoon.
Tip the mixture into four large teacups or ramekins.
Bake at 180 °C for 20 minutes, or until set and springy to the touch.
Remove from the oven and dust with icing sugar.
Slash open the top, pour in some orange liqueur and serve with cream or ice cream.