"I haven't made these but they sound yummy and easy"
( use measuring cup with both cups and mls)
( superfine sugar)
Preheat oven to 250°F.
Beat egg whites until stiff peaks form.
Gradually add sugar and vinegar until thick and glossy.
Place the coffee and water in a small bowl and stir till coffee is dissolved. Gently fold into egg whites. Use a 1/2 inch piping nozzle on to a tray covered with parchment paper, or just spoon. If you don't have a proper nozzle, just put into a ziploc sandwich baggie and cut a half inch hole into a corner.
Cook for 10 to 15 minutes until crisp on the outside. Turn off oven and let them cool completely.