Yukon Gold and Sweet Potato Soup

I always love sweet potato, this is just another great way to use it.  From Readers Digest November 2013.

2 tsp vegetable oil
1 cup onions, chopped
2 tsp garlic, minced (about 2 cloves)
2 cups Yukon Gold potatoes, peeled and cubed
5 cups sweet potatoes, peeled and cubed
3 cups low sodium chicken or vegetable stock
1 tsp dried basil
1/8 tsp each salt and ground black pepper
1/2 cup milk
1/4 cup fresh parsley or basil for garnish, chopped

• In a saucepan, heat the oil over medium heat.  Cook the onions and garlic for 5 minutes or until the onions begin to brown (I always add the garlic later - when the onions are almost done - as it can burn and then taste bitter). 
• Stir in the potatoes, stock, basil, salt and pepper.  Bring to a boil, reduce the heat to a simmer, cover and cook for 20 minutes or until the potatoes are tender.  
• In a food processor or blender, puree the soup with the milk.  Serve sprinkled with the basil.