Preheat your oven to 200 degrees
Sift flour , baking soda, cream of tartar and salt into a mixing bowl
Cut the butter into the flour mix until there are no large lumps left. Should resemble like little pebbles. Pour in the sugar and sultanas and mix.
Whisk the vanilla essence and the buttermilk together in a separate bowl. Pour 3/4 of the milk in first and and mix swiftly (be careful not to over mix) until it starts to come together then add the remainder. Mixture should not be very wet... start with 280ml and ( judge it yourself it should not be very wet)
Put dough onto a lightly floured surface. Flatten it out to around 3/4 cm thickness and use scone cutter or any round shaped cutter to press out the scones
Glaze the top of each scone with some egg wash, followed by an optional sprinkling of sugar. Transfer to floured oven tray.
Bake immediately for 10 /12 mins or until you can see they have become golden brown on the surface