Heat your oven to 180⁰C/350⁰F/gas mark 4 and line two baking trays with baking parchment.
Whisk the egg whites with the salt until they're holding firm peaks but are not stiff.
Gently add in the sugar, spoonful after spoonful, still beating, until you've got a bowl full of snowy meringue.
Sprinkle the cornflour, a few drops of vanilla and the vinegar on top and fold in to combine.
Draw the shapes of 'bones' on each of the parchment-lined sheets.
Spoon the meringue onto the baking parchment into the bone shapes.
Put into the oven, turn it down to 150ºC/300⁰F/gas mark 2 and bake for 30 minutes.
Turn the oven off and leave them in for another 30 minutes, then take out of the oven to cool. Transfer them, on their baking parchment, to wire racks.