Transfer roasted vegetables to a 6- to 8-quart pot and add wine to roasting pan, then deglaze pan by boiling, scraping up brown bits, 1 to 2 minutes. Add wine to vegetables in pot along with water (4 quarts), porcini and soaking liquid, bouquet garni, sun-dried tomatoes, and 2 teaspoons salt. Bring to a boil, then simmer, uncovered, until stock is reduced to about 6 cups, about 2 hours. Pour through a fine-mesh sieve into a large bowl, pressing firmly on and then discarding solids.