Preheat oven to 325°F (163°C). Lightly grease the bottom and sides of a 9-inch springform pan or line with parchment paper.
In a bowl, mix graham cracker crumbs, melted butter, and 1 tbsp sugar until evenly combined.
Press the mixture firmly into the bottom of the prepared pan. Bake for 8–10 minutes, then let cool completely.
In a large bowl, beat softened cream cheese, 1 cup sugar, and cornstarch until smooth and creamy.
Add eggs one at a time, beating on low speed. Use a spatula to scrape down the sides of the bowl. Do not overmix—beat just until combined.
Gently mix in room temperature sour cream, pure vanilla extract, and lemon juice until just combined.
Pour the cheesecake filling over the cooled crust and smooth the top with a spatula.
Bake for 45-50 minutes, or until the edges are set but the center is still slightly jiggly. Let cool completely on a wire rack, then chill in the refrigerator for at least 4 hours, preferably overnight.