Sieve the flour into a warmed mixing bowl. Cream the yeast and sugar in a small basin and add a quarter of the liquid. Make a well in the centre of the flour and add the yeast. Sprinkle over a little flour, cover with a cloth and leave in a warm place until the yeast ferments. Then add the remainder of the liquid, margarine and salt and knead into a smooth dough. Return to the basin, cover with a cloth and leave in a warm place until it has doubled in size. Remove from the bowl and give a further kneading. Then mould into a large round loaf, cover with a cloth and leave in a warm place to "prove" until doubled in size. Finally, wrap the loaf in the large cabbage leaves which have been lightly greased on the inside, tie lightly, and bake in a hot oven, gas mark 6, 200° C (400° F) for approximately 15 minutes.