Preheat the oven to 200°C, fan 180°C, gas 6. Place the pizza bases on separate baking trays and divide the tomato purée between them, spreading it out evenly and to the rim of each base.
Slice the mushrooms and tear the mozzarella cheese into pieces, then sprinkle over the pizza bases.
Top with the Danish salami, sprinkle with dried mixed herbs and bake for 10-12 minutes. Serve with the gem lettuce leaves and sliced cucumber.
Cook's tip: for a veggie alternative, swap the salami for roasted red and yellow peppers.