Preheat your oven to 350 degrees F (175 degrees C) and butter a 9 x 13 baking pan. You can also line your pan with aluminum foil (and butter the aluminum foil) for easy removal of the bars from the pan.
In your stand mixer bowl (or a food processor) combine the butter, sugar, and salt until creamed together. Add in the all-purpose flour and beat until just combined and crumbly. Press the crust mixture into the bottom of the buttered or lined baking pan until the entire bottom is evenly covered with a thin crust layer. Bake for 10-15 minutes, or until the crust is starting to turn golden brown and is no longer doughy to the touch.
In your stand mixer bowl or a large mixing bowl, add sugar, eggs, lemon juice, pineapple juice, and salt. Whisk the wet ingredients together. Puree half of the strawberries in a blender or food processor and add to the wet mixture, then add the chopped strawberries, crushed pineapple, and the lemon zest. Stir to combine then pour the filling mixture over the crust.
Bake at 350 degrees F (175 degrees C) for 40-45 minutes. The filling should not be 'jiggly' and should be golden brown in color. Cool completely to room temperature, then refrigerate for about an hour (it makes removing the bars easier if you didn't use aluminum foil).
*I refrigerated the unused portions for up to 4 days after baking these bars.