Heat olive oil in a deep sauce or soup pot over medium heat.
Saute onion and garlic until onion is translucent, about 5-8 minutes. Measure and add oregano, cumin, chili powder, and cayenne pepper. Stir to combine for a minute.
Add sweet potatoes, lentils, broth, salt and pepper and bring to a boil. Lower to a simmer and cook, stirring occasionally, until lentils and potatoes soften, about 15-20 minutes.
Toss in corn and black beans, stir until heated through, which should just take a minute or two. Pour in coconut milk and stir until the stew thickens somewhat. Taste for seasoning and adjust as desired. If the stew seems too thick, add more broth/water until desired consistency is achieved.
To serve, top with cheese, cilantro, and/or sliced avocado. A nice crusty bread or a handful of tortilla chips are delightful dipping accompaniments, but all of these are optional suggestions.