2 large egg whites, at room temperature
1 pinch of fine sea salt
7/8 cup caster sugar
1 teaspoon cornstarch
1 teaspoon cider vinegar or white wine vinegar
¼ teaspoon ground cardamom
2/3 cup mini chocolate chips
2/3 cup finely chopped pistachios
Preheat the oven to 350 degrees. In a grease-free bowl, whisk together the egg whites and salt until you have soft peaks. Whisk in the sugar a little at a time until thick and gleaming.
By hand, fold in the cornstarch, vinegar and cardamom, then add the chocolate chips and most of the pistachios, and very gently fold these in.
With a spoon, drop mounded blobs of the mixture, 1½ to 2 inches in diameter, onto a large baking sheet lined with parchment paper. Sprinkle with the remaining pistachios.
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.
These are best eaten within 24 hours but can keep up to five days stored in airtight containers. They also can be frozen for up to 1 month.