Place the tortellini in plenty of boiling salted water and cook for about 12 minutes. In the meantime clean, wash and drain the carrots and spring onions. Cut carrots into short, thick sticks, spring onions into fine rings.
Heat the fat in a saucepan. Brown carrots and spring onions in it and deglaze with broth. Bring to the boil and simmer for 2-3 minutes. Wash the tomatoes, dab dry, quarter and remove seeds. Cut tomato quarters into fine cubes.
Wash the basil, dab dry and cut into fine strips, except for a little to garnish. Add the tomato cubes and basil to the hot stock and leave to infuse briefly. Pour the tortellini onto a sieve, rinse under cold water and drain.
Add tortellini to the hot soup and season with salt and pepper. Arrange in deep plates and sprinkle with parmesan. Serve garnished with basil.