In a bowl combine milk and vinegar and set aside to curdle.
In a large bowl, add flour, sugar, salt and yeast.
Add in the curdled milk and mix well.
Now add 1/8 cup of milk and bring the dough together.
It will be firm. Knead for 2 minutes. The dough should not crumble. If it crumbles, add teaspoon of milk to bring it together.
Cover and set aside for 30 minutes.
Preheat oven to 200°C.
Add cold butter and nigella seeds and incorporate them into the dough.
When completely incorporated, dust it with flour (if sticky) and divide into 4 equal portions.
Shape each portion into a disc and place on a greased tray.
Press along the circumference with a fork.
Give a milk wash and bake the biscuits for 20-25 minutes or until golden.
Serve with a cup of coffee.