Pre-heat your oven to 160C Fan/180C/350F/Gas Mark 4, and line a 12 hole cupcake tin with cupcake cases
In a mixing bowl, or a large jug, whisk together the vegetable oil, milk, vanilla extract and vinegar
In another mixing bowl, stir together the caster sugar, self raising flour and baking powder
Make a well in the centre of the flour mixture, and pour in the oil and milk mixture, whisk them together gently with a hand whisk until smooth
Divide the mixture between the 12 cupcake cases. I find it easier to put the mixture into a jug or piping bag to do this as it's quite a wet batter
Bake them for 20-25 minutes or until they are risen and a skewer inserted in the centre of the cupcakes comes out clean. Leave to cool completely on a cooling rack
Make the buttercream by first mixing together the dairy free spread and vegan shortening until combined and smooth. Then add the icing sugar, plant milk and vanilla extract, and mix until smooth. You can do this by hand or for best results use an electric mixer. If the buttercream is too stift, you can add more plant milk
Spread or pipe the buttercream on top of the cupcakes, and decorate with sprinkles if you like
Store in an airtight container in a cool place and eat within 3 days