Peel the potatoes, wash them thoroughly and cut them into quarters. Put the potatoes on a fat pan of the oven, salt and drizzle with olive oil. Clean, wash and roughly dice the peppers. Bake in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for approx. 45 minutes.
Clean the mushrooms, wash them if necessary. Peel and halve onions and cut them into thin strips. Dab schnitzel dry, cut into strips.
Season with salt and pepper. In the meantime wash and grate the cucumber. Peel garlic and press it through a garlic press. Clean and wash the spring onion and cut it into fine rings. Mix quark, cucumber, garlic and spring onion (except for something to garnish).
Season to taste with salt and pepper. Arrange potato vegetables from the tray on plates. Sprinkle a dash of quark with spring onion on top. Add the rest of the quark.