1Melt butter in heavy large pot over medium-high heat.
2Add onions and sauté until golden, about 15 minutes.
3Add carrots and parsnips and cook 10 minutes.
4Add veg broth, potatoes, parsley, pea and thyme. Cover and simmer until potatoes are tender, stirring occasionally, about 30 minutes.
5Bring soup to simmer, thinning with additional broth, if desired. Ladle into bowls and serve.