Mix the flour, salt and yeast in a bowl. Add the water and oil, knead to form a soft, smooth dough. Cover the dough and leave to rise at room temperature for approx. 1½ hrs. until doubled in size.
To deep fry
On a lightly floured surface, roll out the dough to approx. 5 mm thick, sprinkle with fleur de sel. Cut the dough into approx. 20 equal diamonds. Fill a pot to ⅓ with oil and heat it to approx. 170°C. Place the pieces of dough in the oil in batches using a slotted spoon, fry for approx. 3 mins. on each side. Remove and drain on paper towels.
Mix the tomatoes, oregano and oil, season with salt, plate up the gnocco fritto with the cured ham and olives.