Mix the tomatoes with all the other ingredients up to and including the cheese.
Shape the pizza dough into a roll, divide into 12 portions, shape into balls. On a lightly floured surface, roll out the pieces of dough (each approx. 15 cm in diameter). Place 2 tbsp of filling in the centre of each round of dough, shape into balls, press firmly. Arrange the dough balls (seam-side down) in a rectangle on a tray lined with baking paper. Mix the oregano and cheese, sprinkle on top of the pizza balls.
Approx. 30 mins. in the lower half of an oven preheated to 200°C.