Start by frying: Heat the oil in a large
frying pan. Empty the potatoes into the pan,
spread them out to cover the base, then
fry for 5 minutes. Pour in the beaten eggs
so they completely cover the potatoes,
season well and leave the tortilla to cook on
a medium heat for about 15-20 minutes,
or until the base and edges have set.
Grill to finish: Take the tortilla off the
hob and place under a hot grill until the
top is firm, then remove from the grill and
scatter over the tomatoes and mozzarella.
Put the tortilla back under the grill for a
further 3-5 minutes, or until the tomatoes
are soft and the cheese has melted. To
serve, cut into thick wedges.