Preheat the oven to 180°C (350°F). Grease an ovenproof baking dish approximately 20cm in diameter. Glass, Pyrex or ceramic works well.
Beat the egg, sugar and apricot jam with an electric mixer on high for about 5 minutes until pale and thickened.
In a separate bowl, sift together the flour, bicarbonate of soda and salt.
Melt the butter and stir in the vinegar.
With the mixer running, add the flour mixture and the milk alternately in parts until well combined. Add the butter and vinegar mixture and mix through.
Pour the batter into the greased dish. Cover with foil and bake for 45 minutes, until the top is an even golden brown. If it is still pale in the middle, bake a little longer.
While the pudding bakes, make the sauce. Melt the cream, butter, sugar and orange juice together in a pot over medium heat, stirring until smooth and combined.
As soon as the pudding comes out of the oven, pour the hot sauce evenly over the hot pudding. It will look like too much sauce, but it will all absorb.
Leave to stand for 10 to 15 minutes, then serve warm with cream, custard or ice cream.