Clean, trim and halve the mushrooms or cut them into thick slices. Peel and finely chop the onion. Cut sausage into slices. Wash oregano, shake dry and chop the leaves roughly.
Heat the oil in a pan and fry the mushrooms in it. Season the mushrooms with salt and pepper and remove them from the pan. Put slices of sausage and diced onion in the pan and fry briefly. Add tomato paste and sauté, then add tomatoes, stock and oregano.
Let the sauce simmer for about 5 minutes, then season to taste with salt, pepper and sugar. In the meantime prepare noodles in boiling salted water according to the instructions on the packet. Add mushrooms to the sauce, bring to the boil and serve with the noodles.