Place the butter and the sugar into a mixing bowl and using a hand mixer, mix until the sugar and butter are well mixed, and it is nice and soft. It won’t be creamy like cake batter though.
Beat the egg yolks with the whole eggs in a separate bowl and add them to the butter and sugar bowl. Mix well for a couple of minutes and you have a gritty but combined mixture.
Add in the vanilla and the lemon rind and mix again. Add in the lemon juice and mix lightly with a fork. Pour into mason jars and place the lids on but don’t screw them tight.
Place 2 cups of water into the bottom of the Pressure Cooker and place the steamer shelf/trivet on top. Add the mason jars.
Place the lid on the pressure cooker, set the valve to sealing and cook for 12 minutes on manual pressure. After the 12 minutes is up, use natural pressure release for a further 5 minutes.
Use a fork to stir the lemon curd while the mason jars are still in the Instant Pot. Leave for an hour for them to cool down and then fridge them for 12 hours.