01 - Preheat oven to 340°F. Line bottom of a 9-inch springform pan with parchment paper.
02 - Pulse graham crackers in food processor until finely ground. Mix in melted butter, sugar, and salt until combined. Press firmly into bottom of prepared pan. Bake for 10 minutes, then set aside to cool while preparing filling.
03 - In large bowl, beat Greek yogurt, cream cheese, and sugar with electric mixer until completely smooth and creamy, about 2-3 minutes.
04 - Add eggs one at a time, mixing well after each addition. Stir in vanilla extract, lemon zest, lemon juice, cornstarch, and salt until fully incorporated and smooth.
05 - Pour filling over cooled crust. Smooth top with spatula. Bake for 50 minutes until edges are set but center still slightly wobbly.
06 - Turn off oven and crack door open slightly. Leave cheesecake inside for 1 hour to cool gradually and prevent cracking.
07 - Remove from oven and cool to room temperature, about 1 hour. Refrigerate for at least 4 hours or preferably overnight.
08 - Mix sour cream or Greek yogurt with powdered sugar and vanilla until smooth. Spread over chilled cheesecake before serving.
09 - Slice with sharp knife dipped in hot water, wiping blade clean between cuts for neat edges.