Step 1

Preheat the oven to 180C/160C Fan/Gas 4 and line a large baking tray with baking paper. Whisk together the egg whites and salt in a grease-free bowl, until you have soft peaks. Whisk in the sugar a little at a time until thick and gleaming.

Step 2

By hand, fold in the cornflour, vinegar and cardamom, then add the chocolate chips and most of the pistachios and very gently fold these in too.

Step 3

With a spoon, drop mounded blobs of the mixture, 4–5cm/2in in diameter, onto the prepared tray. Sprinkle with the remaining pistachios.

Step 4

Put the cookies into the oven, shut the door and turn off the oven immediately. Let the cookies sit in the turned-off oven overnight.