Make the Strawberry Sauce:

In a saucepan, combine strawberries, sugar, and lemon juice. Cook over medium heat until the mixture thickens slightly and the berries break down (about 8–10 minutes). Stir in cornstarch if needed for a thicker consistency. Let the sauce cool completely before using.

Prepare the Crust:

Preheat oven to 350°F (175°C). In a bowl, mix graham cracker crumbs, melted butter, and sugar until evenly coated. Press the mixture firmly into the bottom of a 9-inch springform pan. Bake for 8–10 minutes, then cool while preparing the filling.

Make the Cheesecake Filling:

In a large bowl, beat cream cheese until smooth and creamy. Add sugar and vanilla extract, mixing until fully combined. Blend in sour cream, then add eggs one at a time, mixing just until incorporated (do not overmix).

Assemble the Cheesecake:

Pour the cheesecake filling over the cooled crust. Drop spoonfuls of strawberry sauce over the top and gently swirl with a knife or skewer to create a marbled pattern.

Bake the Cheesecake:

Place the springform pan in a large roasting pan. Pour hot water into the outer pan until it reaches halfway up the sides (for a water bath). Bake for 55–65 minutes, or until the edges are set and the center is slightly jiggly.

Cool and Chill:

Turn off the oven and leave the cheesecake inside with the door cracked for 1 hour. Then remove, cool to room temperature, and refrigerate for at least 4 hours or overnight before serving.