Put the flour in a bowl, make a depression in the middle, crumble the yeast and add 5 tbsp. lukewarm water. Mix the yeast with the water and some flour from the rim. Cover and leave in a warm place for about 15 minutes until the surface forms cracks
Add 150 ml lukewarm water, 3 tbsp. oil and 1/2 tsp. salt to the pre-dough. Knead ingredients to a smooth, supple dough, dust with flour. Cover bowl with foil or a lid. Let dough rise for about 40 minutes until it is twice as big
Meanwhile, cook the chunky tomatoes in a saucepan for about 3 minutes in an open pan. Season the sauce with salt, pepper, paprika and sugar. Let it cool down a little bit. Peel onions, cut them into rings and fry them in 1 tbsp. oil for about 3 minutes. Let cool down a little. Drain tuna and cut into pieces
Cut the dough in half. Roll out one half (approx. 26 cm Ø) and place it in a pizza tray or on the fat pan of the oven. Spread half of the tomato sauce on the dough. Spread half of the tuna pieces and onion rings on top. Sprinkle half of the cheese on the pizza. Let the pizza rest for about 5 minutes before baking
Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) on the lower rack for approx. 25 minutes. Process the second pizza with the remaining ingredients in the same way
Waiting time approx. 40 minutes