The beauty of dishes like these is that they're so easily tailored to what you have on hand. This recipe was developed based on using spicy refried beans. Whether using plain or spicy, just keep tasting and adjusting the seasonings until you've hit upon the taste that's just right for you. I didn't have any cilantro on hand when I made these, otherwise I would have used it either alone or in combination with the chopped parsley.
Cut the sweet potato into roughly 1-inch chunks, toss it with a bit of oil and roast at 400℉ for 30 to 40 minutes, or until nicely fork tender. If you're having sweet potato for dinner the day before, make extra to use in these cakes — that's kitchen smarts!
Place the roasted and cooled sweet potato into a large mixing bowl and add the refried beans. Using a potato masher, mix together until well incorporated. Don't sweat it if there are some largish streaks of sweet potato … really, there are more important things in life.
Add the prepped aromatics (onion, garlic and chili) and the black beans, as well as the pepper, salt and cumin. Stir together until the beans are evenly distributed, then taste and adjust the seasonings as required. Stir in the splash of vinegar and the parsley and/or cilantro.
Using a 3-ounce ice cream scoop, place a mound of the mixture in the palm of one hand. Pat into a cake that's about 1/2-inch thick and nicely rounded (unlike the one with the jagged protuberance in my photos — oops). Brush a small amount of olive oil on it, then place the oiled side down on the baking sheet. Repeat, and once all the cakes have been formed, brush the tops with just a bit more oil.
Bake for 20 minutes. Serve bottom-side up, or whichever side you think looks more attractive.