Heat oil-water in a large non-stick pan. You will use this pan to both sauté the vegetables and make the pancakes. Add the peppers, most of the scallions, and salt. Cook, stirring occasionally until the peppers start to soften, about 5 minutes. Add the black beans and garlic. Cook for a few minutes more then remove from heat and set aside while you make the batter.
In a measuring cup or small bowl, mix together the milk, oil, and vinegar. In a large bowl, stir together the flour, cornmeal, salt, baking powder, cumin, chili powder, and baking soda. Mix in the wet ingredients. Stir in the cooked vegetables and shredded cheese, if you’re using it.
Wipe out the pan and set it over medium heat. When hot, use a 1/4 cup measure to ladle batter into the pan. Let cook for about 4 minutes, until bubbles start to form on the top, then flip and cook on the other side for another several minutes. Transfer pancakes to a plate and cover with a clean dish towel to keep them warm. Repeat until all the batter is used. If you're doubling the recipe, set the oven to 250ºF and transfer cooked pancakes to a plate in the oven to keep warm while you cook.
To serve, layer pancakes with your favorite toppings. if you're using cheese sauce, layer that in between pancakes as well. Garnish with sour cream, remaining scallions, and fresh herbs.