Preheat the oven to 220ºC/425ºF/gas 7 and place a large flat baking tray upside-down in the oven to heat up.
Add the flours and a good pinch of sea salt to a large bowl and make a well in the middle.
In a jug, mix 325ml lukewarm water with the yeast. Pour the mixture into the well and mix thoroughly, gradually bringing in the flour from the sides until you get a rough dough – if it’s too sticky, add a little more flour.
Knead in the bowl until smooth.
On a flour-dusted surface, split the dough in half. Divide one half into two (for the adults) and the remaining half into 4 (for the kids).
Roll each piece into a ball and place on a semolina-dusted tray, leaving a gap between each one. Cover with clingfilm and place in a warm place to prove for 35 minutes, or until doubled in size.
Next, make the sauce. Peel and finely chop the onion, then clean and roughly chop the mushrooms. Trim and roughly chop the celery and carrot, peel and finely chop the garlic, and pick the oregano.
Heat 3 tablespoons of oil in a medium pan on a medium heat, then add the onion, celery, carrot and garlic.
Cook down for a few minutes, then add the remaining veg, oregano, chopped tomatoes and a good splash of water.
Season lightly with black pepper, then cook for 10 to 15 minutes, or until the vegetables are soft. Blitz until smooth with a stick blender, adding a splash of water to loosen, if needed.
On a flour-dusted surface, press and shape a piece of dough out to the thickness of a pound coin, keeping the crust on the thicker side – this will help hold the sauce.
Drizzle with a little oil, then spoon on a nice layer of sauce, spreading it all over the pizza, stopping 1cm from the edge.
Tear and dot over mozzarella, then top with whatever you fancy – I like finely sliced courgette and red pepper, with some fresh oregano and a small grating of Parmesan, to finish, but feel free to come up with your own combinations.
Pull the pizza onto a flat semolina-dusted tray, then very carefully slide onto the preheated tray that's in the oven. Cook for 7 to 10 minutes for the kids' pizzas and around 15 minutes for the larger ones, or until golden, crispy and cooked through.
Repeat with the remaining dough and keep cooking them as and when you’re ready. Serve with a crisp green salad.