For the dough, dissolve yeast in 150 ml lukewarm water. Knead with 350 g flour, 3 tablespoons oil and 1⁄2 teaspoon salt to a smooth dough. Cover and leave to rise in a warm place for about 45 minutes.
For the sauce boil up the tomatoes. Season with salt, pepper, paprika and sugar and simmer open for about 5 minutes. Let cool off. For the spinach topping peel and chop 1 onion. Fry in 1 tbsp. hot oil.
Add the frozen spinach and 1 tablespoon of water, cover and stew for about 8 minutes. Season with salt and pepper. Let cool off. For the tuna topping, drain the tuna. Peel and halve the red onion and cut into strips.
For the mushroom topping clean, wash and slice the mushrooms.
Knead dough, cut in half. Roll out half on a greased pizza tray (approx. 30 cm Ø). Spread half the sauce on top. Cover each pizza quarter with half spinach, half tuna and half red onion, half mushrooms or salami.
Sprinkle half the cheese on top. Bake in a hot oven (electric cooker: 200 °C/circulating air: 175 °C/gas: see manufacturer) for approx. 25 minutes on the bottom shelf. Bake the rest of the dough and ingredients in the same way for the 2nd pizza.