Prepare the Red Velvet Cake Layer:
Preheat oven to 350°F (175°C). Grease and line the bottom of a 9-inch springform pan. In a large bowl, whisk together flour, sugar, cocoa powder, baking soda, and salt. In another bowl, whisk egg, oil, buttermilk, food coloring, vanilla, and vinegar. Combine wet and dry ingredients until smooth. Pour into prepared pan and bake for 20–22 minutes or until a toothpick comes out clean. Let cool.

Make the Cheesecake Layer:
Lower oven temperature to 325°F (163°C). In a large bowl, beat cream cheese and sugar until smooth. Add eggs one at a time, then mix in sour cream and vanilla. Pour the cheesecake mixture over the cooled red velvet cake layer in the springform pan. Bake for 45–50 minutes until center is set. Cool completely, then refrigerate for at least 4 hours or overnight.

Prepare the Strawberry Topping:
In a small saucepan, combine strawberries, sugar, and lemon juice. Cook over medium heat for 5–7 minutes until strawberries soften. Stir in cornstarch slurry and cook for 1–2 minutes until thickened. Let cool completely before spooning over the cheesecake.

Assemble and Serve:
Once chilled, release the cheesecake from the springform pan. Top with cooled strawberry mixture just before serving. Garnish with extra fresh strawberries if desired.