Spray the inside of a 7 inch spring form pan with non-stick spray
Mix the graham crumbs and melted butter in a small bowl.
Press the graham crumbs into the bottom of the pan and 1 inch up the sides. Set the pan in the freezer while you make the filling.
In a large bowl, beat the cream cheese and sour cream with a hand mixer, or stand mixer, until light and fluffy.
Add the sugar and mix well.
Add the egg yolk and eggs one at a time, mixing between each addition just until blended. Do not over mix!
Stir in the lime juice and lime zest.
Add the corn starch and mix just until blended.
Gently pour the filling into the springform pan and cover pan tightly with foil.
Place 1 1/2 cups of water into the instant pot.
Place the cake on the trivet then gently lower the cake into the pot.
Set to high pressure for 53 minutes. Once the timer is complete allow the pot to naturally release for 10 minutes, then turn the valve to release remaining pressure.
Carefully remove the cake from the pan and remove the foil. Allow to cool for 30 minutes then refrigerate for a minimum of 6 hours, preferably overnight to set.
For the meringue topping
After the cake is completely set you can make the meringue topping.
Beat the egg whites and cream of tarter until peaks begin to form
Add the sugar 1 tablespoon at a time until sugar is dissolved and meringue is glossy and holds stiff peaks.
Spoon the meringue into a piping bag fitted with a start tip and pipe swirls onto the cake. If you don't have a piping bag you can simply spoon the meringue onto the cake and create swirls with a knife.
Using a baker's torch, carefully toast the meringue, being careful not to burn it.
The cake will still be jiggly when you remove it from the Instant Pot. This is normal and it will set as it cools.