Some winter weeks call for food that is warm, filling, cheap, and completely undemanding — and this slow cooker black bean sweet potato stew checks all four boxes without breaking a sweat. Black beans and sweet potatoes are two of the most affordable ingredients in any Canadian grocery store, and together they make a thick, smoky, satisfying stew that happens to be naturally vegan, high in fibre, and freezer-friendly for months. This is also one of the simplest recipes in the whole winter slow cooker lineup. There is no meat to trim, no dairy to temper, no cheese to grate. Everything goes into the cooker at once, and eight hours…