Combine vegetable broth, diced russet potato, 1/4 cup green onions, chopped fresh parsley, chopped garlic, dried thyme and dried sage in large Dutch oven. Simmer over medium heat until potato is tender, about 15 minutes. Add spicy vegetable juice and pasta; simmer until pasta is tender, stirring occasionally, about 8 minutes. Season to taste with salt and pepper.
Ladle soup into bowls. Garnish with remaining 1/4 cup green onions. Sprinkle cheese and croutons over, if desired.
