Sweet potato, carrot, apple, and lentil soup

Delicious warm flavorful soup.  Sweet and spicy all in one spoonful.  Ready in 1 hour 10 minutes.  Serves 6.

Ingredients:
1/4 cup butter
2 large sweet potatoes, peeled and chopped
3 large carrots, peeled and chopped
1 apple, peeled, cored and chopped
1 onion, chopped
1/2 cup lentils
1/2 teaspoon minced fresh ginger
1/2 teaspoon ground black pepper
1 teaspoon salt
1/2 teaspoon ground cumin
1/2 teaspoon chili powder
1/2 teaspoon paprika
2 cans vegetable broth (about 4 cups total)
plain yogurt

Directions:
1. Melt the butter in a large, heavy bottomed pot over medium-high heat.   Place the chopped sweet potatoes, carrots, apple, and onion in the pot.   Stir and cook the apples and vegetables until the onions are translucent, about 10 minutes.

2. Stir the lentils, ginger, ground black pepper, salt, cumin, chili powder, paprika, and vegetable broth into the pot with the apple and vegetable mixture.   Bring the soup to a boil over high heat, then reduce the heat to medium-low, cover, and simmer until the lentils and vegetables are soft.   About 30 minutes.

3. At this point...we cool it for 5 mintues and then eat it.   But, the recipe suggest that you puree it in a blender.   I really prefer the soup sort of chunky, like a stew.   If you choose to puree it, then after it's pureed put it back on the stove to simmer for 10 more minutes.   Add water as needed to thin the soup to your preferred consistency.   Serve with yogurt for garnish (I have not tried the yogurt garnish).