Step 1: Prepare the Crust

1. Preheat your oven to 325°F (163°C). Grease a 9-inch springform pan and line the bottom with parchment paper for easy removal.
2. In a bowl, mix the graham cracker crumbs, sugar, and lemon zest. Stir in the melted butter until the mixture resembles damp sand.
3. Press the mixture firmly into the bottom of the springform pan, ensuring an even layer. Bake for 10 minutes, then set aside to cool.

Step 2: Make the Lemon Cheesecake Filling

1. In a large mixing bowl, beat the cream cheese and sugar until smooth and creamy.
2. Add the eggs one at a time, mixing on low speed to avoid overbeating.
3. Stir in the lemon zest, lemon juice, vanilla extract, and sour cream, mixing just until combined.
4. Pour the filling over the cooled crust and smooth the top with a spatula.

Step 3: Bake the Cheesecake

1. Wrap the bottom of the springform pan with foil and place it in a larger baking dish. Pour hot water into the dish until it reaches halfway up the sides of the cheesecake pan (this prevents cracks).
2. Bake at 325°F (163°C) for 55-60 minutes, or until the center is set but slightly jiggly.
3. Turn off the oven and let the cheesecake cool inside with the door slightly open for 1 hour.
4. Refrigerate for at least 6 hours or overnight to allow the flavors to develop.

Step 4: Prepare the Lemon Curd

1. In a saucepan over medium heat, whisk together the egg yolks, sugar, and lemon juice.
2. Cook, stirring constantly, until the mixture thickens (about 5 minutes).
3. Remove from heat and stir in the butter and lemon zest until smooth.
4. Let cool slightly, then spread evenly over the chilled cheesecake. Refrigerate while preparing the meringue.

Step 5: Make the Meringue Topping

1. In a clean, dry mixing bowl, beat the egg whites and cream of tartar on medium speed until soft peaks form.
2. Gradually add sugar, one tablespoon at a time, beating until stiff, glossy peaks form. Stir in vanilla extract.
3. Spread or pipe the meringue over the lemon curd layer, creating decorative swirls.

Step 6: Toast the Meringue

1. Use a kitchen torch to lightly toast the meringue until golden brown, or place under the broiler for 1-2 minutes, watching closely to avoid burning.
2. Chill for 30 minutes before slicing and serving.