Allow frozen strawberries to thaw. Blend to make a smooth puree. Measure ½ cup of the puree to use in the cake mix and set the rest aside to use in the glaze.
Preheat an oven to 350 degrees F.
Add cake mix, sparkling water or soda, 1/2 of the lemon juice, and ½ cup of strawberry puree to a large mixing bowl whisk until well combined. Evenly coat a 13 x 9 in baking pan with cooking oil spray. Use a rubber spatula to scrape the batter into the bowl and sooth it evenly into the pan. Bake the cake for 23-25. Set aside and allow to cool for 20 minutes.
While the cake is cooling, add confectioner’s sugar, lemon juice, and remaining strawberry puree to a mixing bowl. Whisk until a thick smooth glaze is formed.
When the cake is cool to the touch, drizzle the glaze over the cake, slice, and serve.