Heat oven to 350 degrees Fahrenheit. Grease bottom only of a 13*9 pan with shortening and lightly flour. In a large bowl beat cake mix, water, oil, eggs, gelatin, 1 tbsp lime peel and the rum extract with mixer on low speed for 30 seconds. beat on medium speed for 2 minutes. Pour into pan.
Bake 35 to 40 minutes or until toothpick comes out clean. Cool completely about 1 hour.
Stir 2 Tbsp lime peel into frosting . Spread frosting evenly over cake. Store loosely covered at room temp. Just before serving, cut strawberries in half leaving leaves on. Garnish cake with them.