In a mixer, whisk the whites, cream of tartar, and salt, at low speed, for about 1-2 min until frothy. Slowly add sugar, while whisking, until stiff peaks form, about 5-6 min.
Place in the oven and bake for 1 hour. Then, turn the oven off but leave them in there for 30 min with the oven off so they can firm up. DON’T OPEN THE OVEN DOOR.
Remove from the oven. The meringue kisses should be dry, firm, and crispy but not brown or sticky. Allow them to cool completely before serving. Enjoy!