Heat oven to 350°F (325°F for dark or nonstick pans). Place foil or paper baking cup in each of 12 regular-size muffin cups.
In a large bowl, beat all cupcake ingredients with an electric mixer on low speed for 30 seconds. Beat on medium speed 2 minutes, scraping the bowl occasionally. Divide batter among muffin cups.
Bake 16-18 minutes or until the toothpick inserted in the center comes out clean. Cool 10 minutes; remove cupcakes from pans to cooling racks. Cool completely.
While the cupcakes are cooling, making the frostig. In a large bowl, beat the butter with an electric mixer on low speed until light and fluffy. Gradually add powdered sugar, a few tablespoons at a time. Scrape down the bowl then add the rum and vanilla beat until blended light and fluffy.
Spoon frosting into a piping bag fitted with a star tip. Pipe frosting in circular pattern on tops of cupcakes. Garnish with 1 half a strawberry and lime zest.