Mix together the yeast and warm water
and leave in a warm place for 10 minutes until frothy. Mix the yeast
mixture into the flour, baking powder and salt, then work in the
yoghurt to make a soft dough. Knead until no longer sticky. Place in
an oiled bowl, cover and leave to rise for 8 hours.
Divide the dough into six pieces and roll into ovals about 5 mm or 1/4
in thick. Place on a greased baking (cookie) sheet and brush with
melted butter. Grill (broil) under a medium grill (broiler) for about
5 minutes until slightly puffy, then turn and brush the other side
with butter and grill for a further 3 minutes until lightly browned.