Preheat your oven to 350°F and grease a 9-inch springform pan. For the crust, combine the almond flour, melted butter, sweetener, and vanilla extract in a bowl. Press the mixture firmly into the bottom of the prepared pan. Bake for 10 minutes, then allow to cool.
For the filling, beat the cream cheese and sweetener together until smooth. Add the eggs one at a time, mixing well after each addition. Mix in the sour cream, vanilla extract, lemon juice, and gluten-free flour until just combined. Pour the filling over the cooled crust.
Bake for 50 minutes, or until the center is set but slightly jiggly. Turn off the oven, open the oven door slightly, and allow the cheesecake to cool in the oven for 1 hour to prevent cracking.
For the strawberry topping, combine the strawberries, sweetener, lemon juice, and vanilla extract in a saucepan over medium heat. Cook until the strawberries are soft. Mix the cornstarch with water and stir into the strawberry mixture. Cook until thickened, then cool slightly. Once both the cheesecake and strawberry topping are cooled, spread the topping over the cheesecake. Refrigerate for at least 4 hours, or overnight, until fully set. Serve chilled, garnished with additional fresh strawberries if desired.