Preheat oven to 160°C (140°C fan). Prepare a 20 cm springform pan by greasing and lining the base and sides with baking paper.
Blend biscuits into fine crumbs, then mix with melted butter until it resembles wet sand.
Press the mixture firmly into the base and sides of the pan. Chill while preparing the filling.
Beat cream cheese until smooth. Add flour, vanilla, sour cream, sugar, and lemon zest. Mix gently until combined.
Add eggs one at a time, mixing lightly after each addition until just smooth.
Pour filling into crust. Tap pan to remove air bubbles.
Bake for 55 minutes until slightly set with a gentle wobble in the center.
Turn off oven and cool cheesecake inside with door slightly open for 1 hour, then refrigerate for at least 4 hours.
For topping, cook chopped strawberries, sugar, vanilla, and lemon juice until soft and simmering.
Add cornstarch mixed with water and stir until thickened.
Add halved strawberries and cook briefly. Let topping cool completely.
Spread topping over chilled cheesecake and refrigerate for 2 more hours.
Slice with a clean knife, wiping between cuts. Serve and enjoy.