Preheat oven to 160°C (320°F). Grease a 9-inch springform pan and line the base with parchment.
Combine crushed graham crackers and melted butter; press firmly into the pan bottom to form an even crust. Chill 10 minutes.
Beat room-temperature cream cheese until smooth, scraping sides to avoid lumps.
Add sugar gradually and beat until creamy and combined.
Mix in vanilla, then add eggs one at a time on low speed—do not overmix.
Fold in sour cream (or cream) and flour if using, plus a pinch of salt; mix until just smooth.
Pour filling over chilled crust and smooth the top with a spatula.
Place the pan in a water bath (wrap outside with foil) or set on a baking tray; bake 50–65 minutes until edges set and center slightly jiggly.
Turn off oven, crack door and let cheesecake cool inside 1 hour to prevent cracking; then refrigerate 4+ hours or overnight.
For strawberry sauce: simmer sliced strawberries with sugar and lemon juice until soft; mash slightly and thicken with cornstarch slurry if desired. Cool.
Release springform, transfer cheesecake to serving plate, spoon cooled strawberry sauce over top, and garnish with fresh strawberries before slicing.