Mix the dry ingredients (the flours. sugar, salt and yeast) together in a large bowl or in the bowl of an electric mixer until evenly distributed.
Add the egg, oil and most of the water and mix to form a rough dough. Add water or flour to form a smooth, slightly sticky dough. Knead the dough in a mixer vigorously for about 10 minutes (or 15 minutes by hand), until the dough is very smooth and only slightly tacky.
Place the kneaded dough into a lightly oiled bowl, turn to coat, then cover with plastic wrap to rise until doubled. This will take about 1 1/2 to 2 hours.
Take the dough from the bowl, and, trying desperately not to degas the dough too much, form the dough into a boule. This is best done by stretching the dough from the top away from you towards the bottom. After each stretch, turn the dough by about 45 degrees. When the dough is 'stretched, place it, folds on the bottom, onto a baking tray. Cover the boule with a damp kitchen towel to rest for about 45 minutes.
Start heating the oven (400 F, 205 C) about 30 minutes before baking. Just before baking, slash the bread twice or three times with a serrated knife, spray with a little water and place in the oven.
After about 15 minutes reduce the temperature to 350 degrees. Bake for a total of about 35 to 40 minutes. If you have a baking stone, you can move the boule from the baking sheet to the stone for the last 10 minutes of baking to give more crispiness to the crust.
Cool on a rack.