Sweet potato soup

I got the idea for this recipe from the inside of a Dannon yogurt container foil, but the foil accidentally got thrown away before I made the soup, so I had to wing it on the amounts of everything. Sweet potatoes were only $0.19/lb the week before Thanksgiving, so I bought a ton of them, and this soup was a very comforting, tasty way to use some of them.

Sweet potato soup

2 tsp vegetable oil
1 medium onion, diced (about 1 cup)
1 tsp ground cumin
2 tsp chili powder (by which I mean the spice blend containing cumin, oregano, and ground chiles)
3 medium sweet potatoes (about 10 oz each), cut into 1-inch cubes
1 qt vegetable broth
Pumpkin or squash seeds for garnish, optional
Yogurt for garnish, optional

Saute the onion in the oil until translucent. Sprinkle spices on top and saute another 30 seconds. Add sweet potatoes and broth. Bring to a boil. Reduce heat to a simmer and cook about 20 minutes, or until sweet potato is soft. Use an immersion blender to make it nice and smooth, or process it in batches in a food processor or blender. Garnish with pumpkin seeds and yogurt if desired.

Stirring the yogurt into the soup yields beautiful patterns and reminds me of a scene in "Arcadia."