Vegan Vanilla Cupcakes

• 280 ml soy milk (1 cup + 2 Tablespoons)
• 1 Teaspoon apple cider vinegar (or white vinegar)
• 230 g self-raising flour (1 + ¾ cups)
• ½ Teaspoon baking soda
• 180 g caster sugar (¾ cup + 2 tablespoons)
• 6 Tablespoons sunflower oil (or melted vegan margarine)
• 3 Teaspoons vanilla extract

For the vanilla buttercream:

• 150 g vegan margarine (½ cup + 2 tbsp)
• 500 g icing sugar (4 cups)
• 1 Teaspoon vanilla extract
• 1-2 Tablespoons soy milk (depending on desired consistency)