In a food processor process strawberries until pureed into a liquid.
Strain strawberry liquid through a mesh strainer to remove seeds into a small saucepan. Add the lemon juice to the saucepan and stir to combine.
Heat over medium-high heat until puree is reduced by half (it should be about 1 cup when it is done and thickened), this will take 10-15 minutes.
Cool completely.
Cream together cream cheese and butter until smooth.
Add powdered sugar and salt and beat until light and fluffy, about 3 minutes.
Add ¾ to 1 cup of cooled strawberry puree until you reach the desired consistency and beat well to combine.
Use on your favorite cupcakes, cakes, or even on cinnamon rolls.
Notes
This makes a really big batch of strawberry icing and will be enough to frost a 9 inch cake (including in-between the layers) or to frost 24 cupcakes. You can half the recipe if you'd like.
Make sure you aren't too hasty when it comes to making your strawberry reduction, it should be nice and thick. If it's too thin you'll end up with a thin icing.
I had a little of this leftover after making a strawberry cake and I but it on cinnamon rolls a few days later, it was excellent! It's also really good in between two pieces of graham cracker for a graham cracker icing sandwich (favorite after school snack from my childhood!).