1. In a large pot, heat 2 tablespoons of the oil over moderately low heat. Add the onion and carrots and cook, stirring occasionally, until the onions are translucent, about 5 minutes. Add the zucchini, green beans, 3/4 teaspoon of the salt, and the pepper and cook, stirring occasionally, until the vegetables start to soften, about 5 minutes longer.
2. Add the potatoes, tomatoes, broth, and water and bring to a boil. Reduce the heat and simmer 15 minutes. Add the beans, pasta, and 1 teaspoon of the salt. Continue simmering until the vegetables are tender and the pasta is cooked through, about 10 minutes longer. Remove from the heat.
3. Meanwhile, in a blender or food processor, puree the garlic, basil, and the remaining 4 tablespoons oil and 1/4 teaspoon salt. Stir 1/4 cup of this pistou into the soup. Serve the soup topped with the remaining pistou.
Wine Recommendation: A good German riesling will cut through the richness of the soup and refresh your palate with its lively flavor. Try a kabinett or spätlese wine, preferably halbtrocken (on the dry side).