Fry poblano peppers until the skins are blistered. Peel, seed and devein the peppers. In a skillet, cook onions, peppers and corn for 5 minutes. Add cilantro and cool the mixture. When mixture is cool, add cheese and mix thoroughly. Slice peppers lengthways and stuff mixture until full.
To make the sauce: in a medium saucepan coated with oil, cook onions, garlic, chipotle and oregano for 5 minutes. Add the black beans and water and cook for another 5 minutes. Puree sauce until smooth and season with salt and pepper.
To assemble: spread a pool of the sauce on the bottom of a plate and place chili on top.