I made this very harvest-y meal last night. It is adapted from Moosewood Restaurant New Classic cookbook.
Saute 2 cups of chopped onion in olive oil until soft. Add 2 minced garlic cloves and 1 large diced (~1/2 inch pieces) yam. Cover and cook for 3 minutes. Add one minced chili (as mild or hot as you like), 1 tablespoon coriander, and 1 tablespoon cumin. Stir, cover, and cook for 3 minutes. Add 1 cup of corn and 1 can of black beans. Cover and cook for 10 minutes stirring occasionally.
I like my sweet potatoes to actually be sweet so I drizzled this with a little maple syrup. The cookbook recommends topping it with hot sauce.