Preheat oven to 325°F (163°C). Grease an 8 ½ or 9-inch springform pan.
Make the crust: Mix almond flour, coconut flour, sweetener, melted butter, vanilla, and salt. Press into the pan. Bake for 10-12 minutes.
Make the filling: In the bowl of a stand mixer fitted with the paddle attached, beat softened cream cheese and sweetener until smooth. Add eggs one at a time, mixing after each. Mix in vanilla, sour cream, lemon juice and zest.
Pour filling over the crust. Bake for 50–55 minutes, until edges are set but center is slightly jiggly. Let cool at room temperature for about 40 minutes. While it's cooling, you can loosen it from the sides of the pan, but don't remove the sides completely.
Chill for 8 hours or overnight. When cold and firm, remove the sides and transfer to a plate. Cover the crack with strawberry topping and chill until ready to serve.
To make the topping, thaw the frozen strawberries in a microwave-safe bowl using a low power setting. Drain and reserve the juice. You should have close to ¼ cup, but if you need to add water to make ¼ cup. Put the cold juice in a saucepan and whisk in the sweetener and cornstarch. Bring to a boil and whisk until thick and translucent. Remove from heat and let cool slightly. Pour over the thawed strawberries and let mixture cool. Spread over the cheesecake.