In a large pot, cook the onions in the olive oil until translucent, about 5 minutes. Stir in the oregano, salt, chili powder, cumin, cocoa powder, and corn flour and cook for about one minute more.
While the onions are cooking, purée the chickpeas in a food processor until chunky. Use a little water to loosen the beans if they are too stiff.
Add the remaining ingredients -- the kidney beans, garbanzo paste, chiles, chipotles, and tomatoes -- to the pot, along with the water, and stir.
Bring to a boil, the lower to a simmer and cook, partially covered, for about 1 ½ hours. Taste for seasoning. Serve hot, or better yet, the next day.
