Grease two medium baking trays. Place the yeast and the first measure of flour into a mixing bowl, the bowl of an electric mixer fitted with the dough hook.
Add all the remaining ingredients, except the extra flour, and mix well.
Gradually add sufficient of the extra flour to form a soft dough. Knead for 5 minutes (with the electric mixer), or turn out onto a floured surface and knead by hand for 6-8 minutes, until smooth and elastic.
Sprinkle the dough with flour, shape into a ball and return it to the bowl. Cover, and set aside to rise, until doubled in bulk. Punch the dough down lightly and divide in half.
Set one portion aside. Divide the dough for the first plait in half, making one piece twice as large the other. Divide both portions into 3 balls, so that you end up with 3 large and 3 small balls.
Roll the balls out individually under your palms on a lightly floured surface, so that you end up with 6 strands. Loosely plait the 3 bigger strands together, and, separately, the 3 smaller plaits together, lifting and turning each strand while plaiting to create a bulky, but not flat plait.
You will now have one large and one small plait. Lift the small plait and stretch it slightly to fit nicely on top of the larger one. Tuck the ends of the smaller plait underneath the large plait.
Repeat the procedure for the second loaf. Beat together the egg and water for the glaze, and brush generously onto the plaits.
Place onto the trays, and sprinkle with seeds. Allow the plaits to rise in a protected spot at room temperature, for at least 30 minutes, until doubled in bulk.
Watchpoint: if the dough becomes warm, it will lose shape. Meanwhile, preheat the oven to 170?C.
Bake for 20-25 minutes until the loaves sound hollow when tapped, and the crusts are golden brown and firm. Place on a wire rack to cool.
Makes 2 large loaves