Preheat your oven to 180°C (350°F).
In a mixing bowl, cream together the sugar and eggs until the mixture is light and fluffy.
Add the apricot jam and butter to the sugar and egg mixture. Mix well.
In a separate bowl, sift the flour, baking soda, and a pinch of salt.
Add the dry ingredients to the sugar and egg mixture, alternating with the milk. Start and end with the dry ingredients. Mix until you have a smooth batter.
Lastly, mix in the vinegar. This will cause the batter to foam up slightly.
Pour the batter into a greased ovenproof dish.
Bake in the preheated oven for approximately 35 minutes or until the pudding is golden brown and a toothpick inserted into the center comes out clean.