Preheat your oven to 350°F (175°C) and line an 8x8-inch (20x20 cm) baking pan with parchment paper, leaving an overhang for easy removal.
Begin by making the crust. In a mixing bowl, combine almond flour, coconut flour, melted coconut oil, erythritol, vanilla extract, and salt. Mix until a dough forms.
Press the dough evenly into the bottom of the prepared pan. Bake the crust for 10-12 minutes, or until it starts to turn golden brown. Remove from the oven and let it cool slightly.
While the crust is cooling, prepare the filling. In a separate bowl, whisk together eggs, lemon juice, lemon zest, erythritol, shredded coconut, finely chopped mint leaves, xanthan gum, and salt until well combined.
Pour the filling over the cooled crust and return to the oven. Bake for 15-20 minutes, or until the filling is set and no longer jiggles in the center.
Remove from the oven and allow the bars to cool completely in the pan. Once cooled, lift out the bars using the parchment paper overhang and cut into 12 equal squares.
If desired, garnish with additional lemon zest, mint leaves, or a sprinkle of erythritol before serving.