Step 1

Generously butter the inside of a 7-inch round springform pan. Mix the graham cracker crumbs and the melted butter in a medium bowl, then pour this mixture into the prepared pan. Press this mixture evenly across the bottom and about halfway up the sides of the pan to make a crust.

Step 2

Put the cream cheese and sugar in a food processor, cover, and process until smooth, about 1 minute. Add the eggs one at a time, processing each until smooth. Open the machine, scrape down the inside, and add the sour cream. Cover and process until smooth.

Step 3

Add the lemon zest, lemon juice, vanilla, and salt (if using). Process again until smooth — and again, stop the machine and scrape down the inside. Add the flour and process for 1 minute. Pour this mixture into the prepared crust in the pan (it will rise above the crust on the sides). Do not cover the pan.

Step 4

Pour 1 1/2 cups water into a 6-or 8-quart cooker. Set a heat- and pressure-safe trivet in the cooker. Make an aluminum foil sling, set the filled springform pan on it, and use it to lower the pan into the pot. Fold down the ends of the sling so that they do not touch the batter in the pan. Lock the lid onto the pot.

Step 5

Press Pressure cook (Manual) on High pressure for 25 minutes with the Keep Warm setting off.

Step 6

When the machine has finished cooking, turn it off and let its pressure return to normal naturally, about 20 minutes. Unlatch the lid and open the cooker. Use the sling to transfer the hot springform pan to a wire rack. Cool for 15 minutes, then refrigerate for 1 hour. Cover and continue refrigerating for at least 1 more hour or up to 2 days.

Step 7

To serve, uncover and run a thin knife between the pan and the cake. Unlatch the sides of the pan and open it to remove the cake inside. If desired, use a long, thin knife to slice the cake off the pan’s base and use a large metal spatula to transfer the cheesecake to a serving platter.