Preheat the oven to 180C/160C Fan/Gas 4. Line two 12-hole cupcake tins with 20 paper cupcake cases.
Whisk together the soya milk and cider vinegar in a jug. Set aside.
Cream the sugar and margarine in a large bowl with a hand -held whisk until soft and smooth. Set aside.
Sift the flour, bicarbonate of soda and cocoa powder into a bowl. Mix in the coffee granules and salt, ensuring there are no lumps.
Tip the dry ingredients into the sugar and margarine and pour in the soya milk mixture. Stir together with a wooden spoon, using a figure of eight motion. The mixture will seem dry at first, but will loosen quickly.
Spoon the batter into the cases using a dessert spoon. Be careful not to over-fill.
Bake in the centre of the oven for 25 minutes, or until the cakes spring back to the touch. Leave to cool completely in the tins before decorating.
To make the icing, sift the cocoa and sugar into a food processor and add the shortening. Blend the mixture and gradually pour in the soya milk until your icing is the desired consistency.
To decorate the cupcakes, you can either dollop on some icing and swirl it with a knife, or use a piping bag. See the tips section for other ways to decorate.