Preheat the oven to 180 degrees Celsius and line a cake tin with baking paper.
Sift the flour and baking soda into a large bowl.
Add the sugar and salt and mix well.
Add the soy milk, vanilla, oil and vinegar and whisk until there are no lumps.
Transfer the batter to the cake tin and bake for 30 minutes.
Move to a cooling rack to cool.
Prepare the icing by adding all ingredients to a bowl and mixing with an electric beater.
Add the powdered sugar, vegan butter, vanilla and half of the soy milk.
When your cake is completely cool, ice and add sprinkles.