Heat the oven to 180°C, fan 160°C, gas 4.
Lightly oil a large baking tray or 2 smaller baking trays and put the 4 tortillas on the trays. Spread the tomato purée over the tortillas.
Add your toppings. Just remember that, because the base is so thin, the toppings need to be cut into very small pieces. Bake for 5-8 mins until the base is slightly crisp and the cheese has melted.
Slice the tortilla pizza into strips.