First, my main ingredients included a box of Lemon Cake Mix (from Betty Crocker, of course!), the ingredients listed as necessary for the cake mix (oil, eggs, and water), Lime Juice (fresh squeezed or bottled), and Powdered Sugar.
Mix the cake! Just follow the mixing and baking instructions on the box. Pour the batter into cupcake liners, or a mini bundt cake pan (this is what I was using).
When the cupcakes are cooled (this process can be sped along by placing the cupcakes in the refrigerator), they can be frosted and decorated. To make the frosting/icing you pour some powdered sugar into a bowl (about one cup), and add a small amount of Lime juice while you mix with a spatula or a whisk. Mix until thickened, add more lime juice if it is too powder-y. Add more powdered sugar if it is too liquid-y.
When your icing is ready, spread it onto the cupcakes with a knife or pipe it on with a piping bag (round tip)!
Top with a piece of lime, or sprinkles, and enjoy these sweet, tart cupcakes!