Sweet Potato Bisque

1 tablespoon canola oil
1 medium yellow onion, diced
2 cups rinsed and chopped leeks
2 medium carrots, peeled and diced
2 cloves garlic, minced
4 cups stock
4 cups peeled, chopped sweet potatoes
1/4 cup dry white wine
1 1/2 tablespoons dried parsley
1/2 teaspoon salt
1/2 teaspoon ground white pepper
1 cup milk

Saute onions, leeks, carrots and garlic about 5 minutes.
Add water, sweet potatoes, wine and dried seasonings and bring to a simmer.
Cook over low heat for 25-30 minutes, stirring occasionally.
Remove the soup from the heat and let cook for about 5 minutes.
Transfer soup to a blender and puree until smooth.
Return to pan and stir in milk.
Bring soup to gentle simmer but do not boil.