Adapted from The Guardian
Make the risotto by bringing the stock to the boil in a saucepan.
Add to the pan the rice, salt and saffron. Bring back up to the boil, then turn down the heat and simmer on a medium heat until the stock has been absorbed.
Let risotto cool completely.
Stir the mozzarella into the cool rice then roll a tablespoonful between wet palms to form a ball. Repeat until all the rice is used up.
In a separate bowl, beat together the egg, flour and enough water to make a thick batter (about 175ml), and season. Put the breadcrumbs on a separate plate.
Heat the oil in a deep pan, no more than a third full, to 170C, or until a breadcrumb sizzles on contact.
While you wait for the oil to heat, dip each rice ball into the batter to coat, then roll in the breadcrumbs until well covered.
Cook in batches until golden brown and drain on kitchen towel.