Heat the olive oil in a large pot over medium heat. Add the diced onion and cook until it softens, about 5 minutes.
Stir in the garlic, minced chipotle pepper, cumin, and oregano. Cook for 1 minute until the spices smell fragrant.
Add the diced sweet potatoes and rinsed lentils to the pot. Stir to coat them with the spices.
Pour in the diced tomatoes with their juices and the vegetable broth. Bring the mixture to a boil.
Reduce the heat to low, cover the pot, and simmer for 25 minutes until the lentils and sweet potatoes are tender.
Stir in the corn and cook uncovered for 5 more minutes. Season with salt and black pepper to taste.
Ladle the stew into bowls and top with chopped cilantro. Serve with lime wedges on the side.