In a large, heavy pot, heat oil over medium-high heat. Add the onions, both peppers and garlic and cook until soft, stirring for about 5 minutes. Add zucchini, corn and mushrooms and cook until soft, about another 10 minutes. The liquid will begin cooking out and the edges of the pot should begin to slightly brown.
Add the chili powder, cumin, salt and cayenne, cook and stir until fragrant, about 30 seconds. Add the tomatoes and stir well. Add the beans, tomato sauce and vegetable stock, stir well and bring to a boil. Reduce the heat to medium-low and simmer, stirring occasionally.
Let it cook together for about 35-45 minutes. Remove from the heat and stir in the cilantro and check the seasoning. Adjust if needed. Serve immediately or can be reheated. Enjoy!