Mix the yoghurt with the basil, herb salt and pepper, season to taste and set aside, covered.
Cook the pasta until al dente.
Sauté onion and garlic pieces in oil, add tomatoes and zucchini and let simmer. Now pour in the vegetable stock and simmer uncovered for about 10 minutes over medium heat. Then season with balsamic vinegar, salt and pepper.
Place the pasta on 2 plates, spread the vegetables on top and serve with the yogurt sauce.