Plug in a crockpot and set on high. When the crockpot has heated, add one chopped shallot and cubanelles and garlic. Add some ground black pepper and salt.
Add a tablespoon of water or, if you don't mind some oil, 1 tsp of vegetable oil. Stir well to coat, cover with a lid, and let the mixture cook while you chop the sweet potato.
Add the sweet potato to the pot along with the cumin, oregano and black beans. Add more salt and ground black pepper to taste.
Give everything a good stir, then add 2 cups of vegetable stock. Stir again to mix.
Cover the crockpot with a lid, and let it cook on high about 2 hours or until the sweet potatoes are really soft. Check salt and add more if needed.
Garnish with some cilantro and the chopped shallots or red onions reserved for garnish.
Serve hot with rice.