Preheat oven to 325°F (160°C). Wrap the outside of a 9-inch springform pan with two layers of heavy-duty aluminum foil, sealing all gaps.
Crush graham crackers to fine crumbs. Mix with melted butter and 2 tbsp sugar until the mixture holds together when pressed. Press firmly into the pan base. Bake 8 minutes. Let cool.
Beat cream cheese alone on medium speed for 2 full minutes until completely smooth — no lumps or streaks.
Add 200g sugar and beat 1 minute. Add sour cream, vanilla, and lemon zest if using. Mix on low for 30 seconds.
Add eggs one at a time on the lowest speed, mixing only until the yolk disappears (~15 seconds each). Stop immediately after the last egg.
Pour filling over cooled crust and smooth with an offset spatula. Place springform pan in a large roasting pan. Pour hot tap water into roasting pan halfway up the springform pan sides.
Bake 55 to 65 minutes. Edges should be set; center should wobble as a single mass. Turn oven off, crack door 1 inch, leave inside 1 hour.
Remove from water bath. Run a thin knife around the inside edge of the pan. Cool at room temperature 1 hour, then refrigerate a minimum of 4 hours (overnight preferred).
Release the springform ring, slice with a hot clean knife, and serve.