Sweet Potato and Lentil Soup

I LOVE this soup - its hearty and good for you, and very flavorful! We often eat it with grilled cheese sandwiches for dinner!

3 sweet potatoes or yams, peeled and chopped
3/4 Cup dried lentils
5 teaspoons fresh basil, diced
5 teaspoons fresh parsley, diced
1 medium to large red onion, diced
2-3 Tablespoons Olive or Grapeseed oil
3-4 Cubes Vegetable Stock (if keeping it vegetarian, otherwise chicken stock cubes are fine)
Water
Salt and Pepper to taste
Parmesian cheese for garnish

Fill a large pot 3/4 of the way full with water and throw in the stock cubes. Add the oil, onion, parsley and basil. Bring to a boil. When mixture is boiling add the lentils and sweet potatoes, cover and simmer 30 minutes. Salt and pepper to taste (I like to use lots of fresh ground pepper and kosher salt for the best flavor) and return to a low simmer, until the potatoes and lentils are soft. Serve garnished with freshly ground parmesian cheese.