Preheat your oven to 350 degrees.
Grease or line a 13x18 in baking sheet.
Start by creaming together the butter and sugar until light and fluffy in your mixer.
Add eggs one at a time, mixing in between each addition.
Add vanilla, lemon juice, and zest.
In a separate bowl, mix flour, salt, and baking soda.
Add the flour mixture to the butter/egg mixture in 1 cup increments, mixing well after each addition.
Stir in poppy seeds.
Spread dough on to the baking sheet and bake for 15-20 minutes or until a toothpick is inserted and comes out clean.
To make the frosting-
Place strawberries in the bowl of a small food processor; process until pureed.
In the bowl of an electric mixer fitted with the paddle attachment, beat together butter and salt on medium speed until light and fluffy.
Reduce mixer speed and slowly add confectioners' sugar; beat until well combined.
Add vanilla and 3 tablespoons strawberry puree (save any remaining strawberry puree for another use); mix until just blended. Do not overmix, or frosting will incorporate too much air.
Frosting consistency should be dense and creamy, like ice cream.
Frost cooled lemon sugar cookie bars and cut to serve.
Makes 15-18 bars.