Crumble the fresh yeast into a bowl, pour in the tepid water and stir gently until smooth. (For dried yeast, dissolve the sugar in the tepid water then sprinkle the yeast over the surface. Leave to stand in a warm place for about 20 minutes, or until frothy, whisking occasionally.)

Sift the flour and cornflour with the salt into a large bowl and stir in the sugar. (If dried yeast is being used the sugar will already be incorporated.) Make a well in the centre of the dry ingredients and pour in the yeast liquid. Using a wooden spoon gradually beat the flour into the well of liquid until a firm dough is formed.

Turn the dough out on to a lightly floured surface. Rotate the dough with one hand and with the heel of the other, push and stretch the dough from the centre outwards. Continue kneading this way for about 4 minutes, or until the dough is smooth.

Lightly oil a large mixing bowl and put the kneaded dough in it. Cover the bowl with oiled cling film or a damp tea-towel and stand it in a warm, not hot, place for about 1 hour, or until the dough has doubled in size.

Halve the dough and knead each piece until just smooth. On a well floured surface roll each piece out to an oblong about 35.5 x 15 cm (14 X 6 inches) leaving the ends rounded off. Carefully roll up the dough from the long side like a Swiss roll. Place the rolls, seam side down, on well floured baking sheets.

Using a sharp knife make shallow slashes along the top of the dough at 4 cm (1 1/2 inches) intervals. Beat the egg with a good pinch of salt and brush over the surface of the loaves.

Put the loaves in a warm place, uncovered, until trebled in size, 20 - 40 minutes. They should feel springy to the touch.

Heat the oven to 220°C (425°F) mark 7 and place a roasting tin of hot water in the base. Bake the loaves for 15 minutes then remove the pan of water. Continue baking the loaves for a further 8 - 10 minutes or until well browned and really crisp. The loaves should sound hollow when tapped. Ease off the baking sheets and cool on wire racks.