Preheat the oven to 180°C/ 350°F. Line a muffin tin with 12 muffin cases.
In a large mixing bowl, cream together the dairy-free spread and sugars with a wooden spoon. Stir in the vanilla extract.
In a separate bowl, mix together the flour, cocoa powder, baking powder, bicarbonate of soda, and salt. Alternate adding the dry ingredients and the soy milk to the larger bowl in 4-5 increments, folding after each addition.
Stir in the lemon juice. As the lemon juice reacts with the bicarbonate of soda, the mixture will increase in volume. Fold gently so as to not lose any air bubbles.
Divide the cupcake batter between the 12 muffin cases. Tip: use a ladle or ice cream scoop to evenly portion out the mixture!
Bake the cupcakes for 15-20 minutes at 180 degrees until a toothpick inserted comes out clean. Leave to cool in the tin for a few minutes, then transfer to a wire rack to cool completely.