Part 1: Making and Baking the Gluten-Free Tart Crust

1. Preheat and Prep: Preheat your oven to 350°F (175°C). Have a 9-inch tart pan with a removable bottom ready. You do not need to grease the pan.

2. Combine Dry Ingredients: In a food processor, add the almond flour, oat flour, powdered sugar, and sea salt. Pulse a few times to combine.

3. Cut in the Fat: Add the cold, cubed coconut oil or butter to the food processor. Pulse in short bursts (about 10-15 times) until the mixture resembles coarse, damp sand with some pea-sized bits remaining.

4. Form the Dough: If the dough seems too dry and won’t hold together when pinched, add 1 tablespoon of ice water and pulse again. Add another tablespoon only if absolutely necessary. Be careful not to over-process.

5. Press into Pan: Transfer the crumbly dough into the tart pan. Using your fingers and the flat bottom of a measuring cup, press the dough firmly and evenly across the bottom and up the sides of the pan. Ensure the sides are a consistent thickness to prevent them from burning.

6. Dock the Crust: Use a fork to gently prick the bottom of the crust all over. This prevents the crust from puffing up while it bakes.

7. Blind Bake: Place the tart pan on a baking sheet (to catch any potential drips) and bake for 15-20 minutes, or until the edges are golden brown and the center looks dry and set.

8. Cool Completely: Remove the crust from the oven and place it on a wire rack to cool completely. It is crucial that the crust is at room temperature before you add the filling.

Part 2: Preparing the Silky Lemon Curd

1. Combine Ingredients: In a medium-sized, non-reactive saucepan (like stainless steel), whisk together the egg yolks, whole eggs, granulated sugar, fresh lemon juice, lemon zest, salt, and cornstarch. Whisk thoroughly until the mixture is smooth and there are no lumps of cornstarch.

2. Cook the Curd: Place the saucepan over medium-low heat. Cook, whisking constantly, scraping the bottom and corners of the pan. Do not walk away, as the eggs can scramble easily.

3. Thicken: Continue whisking until the mixture thickens significantly. This will take about 8-10 minutes. You’ll know it’s ready when it’s thick enough to coat the back of a spoon, and when you run your finger through it, the line holds its shape.

4. Add Fat and Strain: Immediately remove the saucepan from the heat. Add the cubed coconut oil or butter and whisk until it has completely melted and the curd is smooth and glossy. For an extra-silky texture, pour the curd through a fine-mesh sieve into a clean bowl. This will catch any tiny bits of cooked egg or zest.

Part 3: Assembling Your Masterpiece

1. Fill the Crust: Pour the warm lemon curd into the completely cooled tart crust. Use an offset spatula or the back of a spoon to spread it into an even layer.

2. Chill to Set: Carefully place the tart in the refrigerator. Let it chill for at least 4 hours, but preferably overnight. This chilling time is non-negotiable; it allows the curd to set firmly so you can get clean, beautiful slices.

3. Decorate and Serve: Just before you are ready to serve, arrange the fresh blueberries over the top of the set lemon curd. You can create a pattern, cover the entire surface, or make a simple crescent shape along one edge.

4. Slice and Enjoy: Carefully remove the outer ring of the tart pan. Slice with a sharp knife, wiping the blade clean between each cut for the neatest slices.