Make the sponge. Put the currants and lemon juice into a small saucepan over a medium heat and bring to the boil. Remove from the heat, stir in the bicarbonate of soda and leave the fruit to soak for at least an hour (overnight is better!), until plump. Drain the currants to remove the liquid.

Put the flour, baking powder, vegetable suet, cane sugar, lemon zest and drained currants into a mixing bowl and mix to combine. Add the milk and stir to make a soft dough.

Lay out a large sheet of tin foil and on top, lay parchment paper and make a pleat in the paper and tin foil so that the sponge can swell. Butter the paper. Tip the sponge onto the paper and form a long sausage shape. Roll it up, making sure that the tin foil is well sealed to keep all the water out.

Put a steamer (or metal colander) above a pan. Fill the pan two-thirds of the way up with just-boiled water.

Cover the steamer with a lid (or with more tin foil), and place it on a medium-high heat and bring the water back to the boil. Then, reduce the heat and simmer for at least 1½ hours, until the foil top has risen a bit and the pleat is stretched slightly.

Make the custard. Put the milk into a pan and heat, being really careful not to burn the milk.

Place the egg yolks, sugar and cornstarch/cornflour into a bowl and whisk together until combined. A little at a time, pour the warm milk mixture onto the eggs, stirring continuously with a balloon whisk. Pour the mixture back into the pan and cook over a low heat, stirring with a wooden spatula, until the custard is just thickened.

Once the steaming time is up, carefully remove the pudding from the pan. Leave it to cool for 3 minutes, then unwrap. Serve in slices with golden syrup and custard so that your friends and family can make the dish as sweet and moist as they like.