1. Sift the baking powder, bicarbonate of soda, flour, salt and sugar into a bowl,
2. Stir in the natural yogurt and about 150 ml (1/4 pint) water and bind to a smooth, soft but manageable dough. Knead dough lightly.
3. Shape into a 15 cm (6 inch) round. Make two or three slashes across the top. Place on a buttered baking sheet and bake in the oven at 190°C (375°F) mark 5 for about 40 minutes until the base sounds hollow when tapped. Cut into wedges for serving.