In a measuring jug, mix 150ml (5fl oz) of the warm water with the caster sugar and the dried yeast or the fresh yeast or the fast-acting yeast, whichever you're using. Leave to stand in a warm place for five minutes or until the mixture is creamy. If you're using fast-action yeast, there is no need to let the mixture stand.
Sift the strong white flour and the salt into a large bowl, or into the bowl of an electric food mixer fitted with a dough hook. Make a well in the centre.
Pour the extra-virgin olive oil into the remaining 275ml (10 fl oz) of warm water.
Pour the yeast mixture into the well in the flour along with most of the warm water and olive oil mixture.
Mix to a loose dough, adding the rest of the warm water and olive oil mixture if needed; if the dough still seems a little stiff, add more water if necessary.
Knead the dough by hand for about 10 minutes – or five minutes in a food mixer – until dough is smooth and springy to the touch.
Put the dough in a large, oiled bowl and then cover the top tightly with cling film. Put the bowl somewhere warm for up to two hours so the dough can rise (up to three hours on a cold day) or until it has doubled in size.
When the dough has more than doubled in size, knock it back and knead it again for 2-3 minutes. Leave it to relax for about 10 minutes before you begin to shape it into rolls. Divide the dough into 12 pieces that are roughly the same size. Shape each piece of dough into a rough ball, then transfer it to a baking sheet and cover with a tea towel.
Allow the rolls to prove in a warm place for 20-30 minutes or until they have roughly doubled in size. When they are fully risen, when you press the dough with your finger, it should leave a dent.
While the rolls are proving, pre-heat the oven to 220°C, 425°F, Gas 7.
Brush each of the rolls with the beaten egg and sprinkle with sesame seeds, then bake them in the oven for 15 minutes. Then turn the heat down to 200°C 400°F, Gas 6 and continue to cook for about 10-20 minutes. When they are cooked, the rolls should be nicely browned and they should sound hollow when they are tapped on the base. Transfer the rolls to a wire rack to cool completely. Dust with strong white flour, if you are using it.