Thaw the frozen vegetables in a saucepan adding 1 tablespoon water. In the meantime, cut the spring onions into rings, cut the mushrooms into thick slices, cut in half and add both to the vegetables in the pot. Steam everything, stirring occasionally.
Mix the chunky tomatoes with the vegetables and pour in approx. 250 ml vegetable stock. Bring to the boil and then stir in the raw pasta, bring to the boil again and simmer with the lid half closed until the pasta is still firm to the bite. Season to taste with salt and pepper and, if necessary, add the rest of the broth. Stir again and again.