Preheat your oven to 350°F (175°C).
In a mixing bowl, combine the almond flour, coconut flour, maple syrup or agave nectar, melted coconut oil, and a pinch of salt. Stir well until everything is thoroughly combined and the mixture has a crumbly texture.
Press the crust mixture into the bottom of a tart pan, making sure to cover the base and the sides evenly. Use your fingers or the back of a spoon to press it down firmly.
Place the crust in the preheated oven and bake for about 10-12 minutes, or until it turns golden brown. Remove from the oven and let it cool completely.
While the crust is cooling, prepare the lemon filling. In a saucepan, whisk together the coconut milk, lemon juice, cornstarch, maple syrup or agave nectar, lemon zest, and a pinch of turmeric (if using) until well combined.
Place the saucepan over medium heat and cook the mixture, stirring constantly, until it thickens and comes to a gentle boil. This should take about 5-7 minutes.
Once the filling has thickened, remove it from the heat and let it cool slightly. Then, pour the lemon filling into the cooled tart crust, spreading it out evenly.
Place the tart in the refrigerator and let it chill for at least 2 hours, or until the filling sets.
Once the tart has set, you can garnish it with additional lemon zest or slices if desired. Slice and serve!