Preheat your oven to 350°F (175°C) and line a muffin pan with cupcake liners.

In a large mixing bowl, combine granulated sugar, all-purpose flour, baking powder, baking soda, salt, lemon zest, and lime zest.

Add softened unsalted butter to the dry mixture and blend until it resembles a fine crumb.

Whisk together eggs, sour cream, vegetable oil, and vanilla extract until smooth.

Pour the wet mixture into the dry ingredients and stir gently until just combined, then add grenadine and water.

Fill each cupcake liner about three-quarters full with the batter and bake for approximately 14 minutes.

Allow cupcakes to cool in the pan for about 5 minutes and then transfer to a wire cooling rack to cool completely.

Beat unsalted butter until light and fluffy, then gradually add powdered sugar and grenadine, mixing until creamy.

Frost the cooled cupcakes with the pink buttercream and top each with a maraschino cherry.