I got this recipe from the Betty Crocker website. I haven't made it yet, but it's definitely on my list of things to make this summer. If you get to make this before I do, please let me know how it turns out.
Heat oven to 350°F Grease bottom only of 13x9-inch pan with shortening or spray bottom with cooking spray.
In large bowl, beat cake mix, water, drink mix (dry), 1 tablespoon lime peel, the rum extract, thawed strawberries and eggs with electric mixer on low speed 30 seconds. Beat on medium speed 2 minutes, scraping bowl occasionally. Pour into pan.
Bake 30 to 35 minutes or until toothpick inserted in center comes out clean. Cool 15 minutes.
If using the recommended frosting, uncover tub of frosting and remove foil. Microwave frosting on High 20 to 30 seconds or until pourable. Stir in 2 teaspoons lime peel. Pour frosting over cake; spread evenly. Serve warm or cool. Store loosely covered at room temperature. Just before serving, cut whole strawberries in half, leaving leaves on. Garnish cake with strawberry halves.