I've made this twice and both time the primary reason has been that I had all the ingredients and I desperately didn't want to go to the store.
It's also ridiculously good. I cannot believe this is a vegan recipe - it's so creamy and has a little bit of a sweet taste because of the sweet potatoes and the second time I made it, I took most of it to a friend's house (she'd just broken her collarbone) and Bart and I were absolutely scraping the bottom of the crockpot for the remainders.
I don't know that you could make a much cheaper meal than this one, either. I think the whole pot cost about $2. Just one more reason to love vegetarian cooking.
Crockpot Sweet Potato & Black Bean Soup
(adapated from Kalyn's Kitchen)
1½ cups dried black beans, rinsed (or 3 cans black beans, drained and rinsed)
1 large or 2 medium sweet potatoes, diced
½ large onion, diced small
1 t minced garlic
4 cups vegetable stock (or chicken stock, if you don't care about it being truly vegetarian)
3/4 t ground coriander
1 t ground cumin
½ t black pepper
1 t salt (omit if you've used canned beans)
2 T lime juice
Pour the beans, diced sweet potato, diced onion and garlic into a crockpot. Pour the vegetable stock over the top and sprinkle on the spices (do not add lime juice). Stir to combine, put the lid on and let cook on low for 8 hours (or on high for 5 hours).
When the beans and potatoes are very soft, stir in lime juice and blend with an immersion blender until mostly smooth (I like to leave some small chunks) (alternatively, use a traditional blender and pulse to get it mostly smooth). If it's too thick, add some more broth to thin it out.
Salt to taste (mine needed about a tablespoon more salt because my vegetable stock is not very salty at all) and serve.