Cook the tortellini in boiling salted water for about 15 minutes and drain. In the meantime, clean, wash and chop the beans and celery. Cook the beans in boiling salted water for about 15 minutes and drain. Wash, clean, quarter and seed the tomatoes. Cut the flesh in half again.
Wash the basil and pluck the leaves from the stems. Heat the oil in a pot. Sauté the celery in it. Add beans, tomatoes, basil and bay leaves. Fill up with 3/4 litre water and bring to the boil. Stir in stock. Heat up tortellini in it. If necessary season again with salt and pepper. Roast pine nuts in a pan without fat, slice parmesan thinly.
Fill up with 3/4 litre water and bring to the boil. Stir in stock. Heat up tortellini in it. If necessary season again with salt and pepper. Roast pine nuts in a pan without fat, slice parmesan thinly. Sprinkle both over the stew and serve