Pour one litre of boiling water over the mushrooms and let them swell for about 20 minutes. Clean and wash the bell peppers and cut them into thin strips. Wash the sprouts and let them drain. Clean and wash spring onions and cut them into pieces.
Drain mushrooms on a sieve. Heat the oil in a pan and fry the spring onions, peppers, sprouts and mushrooms for about 2 minutes at low heat. Roll out half of the yeast dough on a floured work surface to a circle (approx. 32 cm Ø), place on a baking tray lined with baking paper. Spread the sauce, steamed vegetables evenly on the base, sprinkle with cheese and bake in a preheated oven (electric cooker: 200 ° C / gas: level 3) for 20-25 minutes