Preheat the oven to 320°F (160°C). Line an 8-inch springform pan by placing a square of parchment over the upside-down base and clipping it into place. Butter the base and sides lightly.

Crush crackers in a food processor until fine. Add melted butter and pulse until combined. Press mixture into the base and sides of the prepared pan using a measuring cup. Chill while preparing filling.

In a large bowl, beat cream cheese until just smooth (about 20 seconds). Add flour and mix briefly. Add vanilla, sour cream, sugar, and lemon zest. Beat until just combined. Add eggs one at a time, mixing briefly after each.

Pour the filling into the crust. Bake for 55 minutes until lightly golden and slightly jiggly in the center. Turn off the oven, crack the door open, and let it cool inside for 1 hour. Refrigerate in the pan for at least 4 hours.

In a saucepan, combine diced strawberries, lemon juice (or water), sugar, and vanilla. Simmer for 10 minutes. Stir in cornstarch mixed with water. Add halved strawberries and cook 1 more minute. Let cool until syrupy.

Spread cooled topping over chilled cheesecake. Arrange strawberry halves face-down. Chill at least 2 hours before slicing and serving with extra sauce.