Mix the yoghurt, oil, margarine, salt, red pepper and bicarbonate of soda. Add as much flour as needed to make a dough the texture of "an ear lobe" (a Turkish expression).

Spread the dough into a round cake pan 30 cm. in diameter. Trace crossed lines in the dough to make diamond shapes. Brush with egg yolk. Sprinkle with the grated cheese (Cantal, Kashar or Gruyere). Bake in a medium oven until the surface becomes golden brown.