Yum.  Nuf said.
Ingredients
2 tbls vegetable or canola oil
1/2  of a yellow onion, finely chopped
6-8 cloves of garlic, minced
2 medium sweet potatoes, diced into 1/4-inch cubes
2 tbls chili powder
1 tbls cumin
1 1/2 cups vegetable stock
1 15-ounce can diced tomatoes
1 15-ounce can crushed tomatoes
1 15-ounce can kidney beans, drained
1 15-ounce can black beans, drained
Salt & pepper to taste
Directions
In
 a large pot or dutch oven, heat two tablespoons of vegetable or canola 
oil over medium heat.  Add the chopped onions and saute until 
translucent, about 5-7 minutes.  Then add the garlic and sweet potatoes,
 and saute for another 5 minutes.  
Add in the chili powder and 
cumin and stir to coat the vegetables in the spices.  Pour in the 
vegetable stock and using a spoon, scrape the bottom of the pan to get 
all of the spices off the bottom.  Add the two cans of tomatoes and 
stir.  Bring to a boil, then reduce heat to medium and allow to simmer 
covered for 10 minutes.  
Add the beans to the pot, and 
check for seasonings.  Add salt & pepper at the time if you need 
it.  Cover and let simmer for another 10 minutes.  Recheck for 
seasonings and serve.