To make the pizza base, sift the flour and salt into a large bowl, then stir in the sugar and yeast. Measure 380ml lukewarm water in a jug. Make a well in the centre of the flour and pour in the water. With lightly oiled hands, mix the flour into the liquid until it comes together.
Dust a work surface with a little flour. Tip out the dough, scraping out any that sticks to the bowl. Knead for 5-10 minutes until smooth, soft and slightly elastic (it will spring back to shape when you press it). Put in a lightly oiled bowl, cover and leave in a warm place for 1 hour until doubled in size.
Preheat the oven to 220°C, fan 200°C, gas 8. Line 2 baking sheets with greaseproof paper. Gently knock the air out of the dough, tear off one fifth, and set aside to make dough balls.
Divide the remaining dough in half and knead each piece briefly on a lightly floured surface. Roll and pull the dough gently with your hands, stretching it out into a circle measuring about 27cm across. Put the bases on to the baking sheets.
Spread each base with the passata and scatter over half of the mozzarella. Arrange the salami and mushrooms around the outer edges of the pizzas – this will be for the adults. Let the kids fill the middle part of the pizza with the peppers and cherry tomatoes, and scatter the remaining mozzarella over the whole pizza.
Bake in the oven for 10-12 minutes until the bases are crisp. Serve with the salad.