Heat the oven to 325°F (163°C). Grease a 9-inch springform pan and wrap its outside with heavy-duty foil for the water bath. Mix the graham cracker crumbs, melted butter, and 1/4 cup sugar. Press firmly over the bottom of the pan and bake for 8 minutes. Cool while you make the filling.
Beat the cream cheese on low speed until smooth. Add the remaining sugar, flour, and salt; mix just until combined. Add the eggs one at a time, scraping the bowl. Stir in the sour cream and vanilla without overbeating.
Pour the filling over the crust. Set the pan inside a larger roasting pan and pour hot water into the outer pan to reach about halfway up the springform sides. Bake for 60 to 70 minutes, until the edges are set and the center still has a slight wobble.
Turn off the oven, crack the door, and leave the cake inside for 1 hour. Remove it from the water bath, cool completely, cover, and refrigerate for at least 6 hours before serving.
