Preheat oven to 350℉ (175℃). Grease an 8x8 baking dish or line it with parchment paper and set aside.
For the Shortbread Base and Crumble: In a food processor fitted with an s-blade, combine 1½ cup all-purpose flour, ⅓ cup granulated sugar, dash table salt, and cubed butter. Pulse together until pastry dough is crumbly and butter is evenly distributed. Remove ½ cup mixture for the crumble topping.
Press the remaining shortbread mixture into the prepared baking dish and bake for 15 minutes.
While crust is baking, combine ½ cup full-fat sour cream, ¼ cup granulated sugar, 1 teaspoon vanilla, 1 large egg, 1 teaspoon lemon zest, and 2 teaspoons fresh lemon juice together. Gently fold in diced strawberries.
When the crust comes out of the oven, pour the strawberry batter over the crust and sprinkle the reserved ½ cup crust batter over the berry mixture evenly.
Return to the oven and bake for 45-50 minutes or until pie bars are set and crumble over top is slightly browned.
Allow the bars to cool for at least an hour at room temperature, then cover, and chill in the refrigerator for 2 hours before slicing into bars.
Notes
No Food Processor? If you don't have a food processor, use 2 forks or a pastry mixer to combine strawberry bar crust. Strawberries: For best results, use fresh ripe strawberries. Do not use frozen strawberries.Sour Cream: Use full-fat, or fat-free plain Greek yogurt of the sour cream if desired. Do not use fat-free sour cream.Storage: These bars taste best after being refrigerated overnight. They can be stored in an airtight container in the refrigerator for 4-5 days. I don't recommend freezing.Note on Doubling Recipe: To double the recipe, use a 9x13 baking dish and 1 cup (instead of ½ cup) of the shortbread mixture for the crumble.