Baby Girl Strawberry Frosting

I really wanted to do strawberry frosting from scratch for cupcakes I made for Angela's baby shower. (Girl. Duh.) I ended up using a mash-up of two recipes; one was the Sprinkles recipe from Martha Stewart's website and the other from a blog called Recipe Shoebox. I made the cupcakes from scratch also, but they came out pretty dry, so I don't think I'll post the recipe I used.
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4-6 whole frozen strawberries, thawed
3/4 cup butter, slightly cold
1/4 cup shortening
3 cups powdered sugar
1 tsp vanilla
3 tsp lemon juice
pinch of coarse salt

In a small bowl, mash strawberries.

In a medium bowl, beat together butter, shortening and salt until fluffy. Reduce mixer speed and slowly add powdered sugar until it is the consistency of ice cream.

Add 3 Tbsp of the mashed strawberries, the lemon juice and vanilla. Mix until just blended.