Make The Graham Cracker Pistachio Base: Heat oven to 350°F and arrange a rack in the middle. Coat a 13-by-9-inch baking dish with coconut oil and line the pan with 2 pieces of parchment that overhang each side of the pan by 1 inch
In a food processor, finely grind pistachios with graham-cracker crumbs and 1 3/4 teaspoon of salt until it resembles a fine meal. Add 1/4 cup of the honey and coconut oil and process until mixture is thoroughly moistened and it begins to lump together about 30 seconds.Press mixture into the bottom of a prepared pan. Bake until lightly browned, 10 to 12 minutes. Remove from the oven and let cool while you make the filling.
Make The Strawberry Lemonade Filling: Place strawberries in the food processor and process until they’re a super smooth purée. Pass strawberry purée through a fine mesh sieve and press on the sieve with a spatula to extract as much of the purée as possible; discard any seeds.Combine purée with the remaining 1/2 cup of the honey, salt, and all other ingredients aside from powdered sugar in a large non-reactive bowl and whisk until sugar is dissolved and mixture is smooth about 2 minutes.
Bake The Bars: Pour filling over the baked crust, return to the oven, and bake until just set in the middle, about 25 to 30 minutes. Remove from the oven and let cool completely on a wire rack, about 1 hour. Cover and place in refrigerator to set up for 2 to 3 hours.
Cut And Serve: Using a knife dipped in hot water, cut into squares, then, as desired, top with powdered sugar or toasted coconut flakes and serve.