Preheat oven to 350oF (180oC).Line a standard 12 cups muffin pan with cupcake liners. Set aside.
To a bowl, add sugar, lemon juice and water. Whisk until sugar is completely dissolved.
Then add oil and mix well.
Add vanilla extract and mix well.
Sift in flour, baking powder, baking soda and salt.
Mix until dry flour is no longer visible. DO NOT OVER MIX (mix until dry and wet ingredients are just combined).
Divide the batter into 2 parts.
To one part, add a drop of yellow food coloring gel.To the other part of the batter, add a drop of blue food coloring gel.Mix well and transfer each batter to a piping bag (14 inch, 36 cm).Cut the tip of the piping bags and place them inside a larger piping bag (21 inch, 53 cm)
Pipe the batter into the cupcake liners.
Bake in preheated oven to 350oF (180oC), rack middle position, 18-20 minutes, or until toothpick inserted in the middle of cake comes out clean.
Let cupcakes cool down in pan for 10 minutes. Then transfer cupcakes to wire rack to cool down completely.