In a large skillet, warm the olive oil over medium heat. When the oil is hot, add the onion, bell pepper and zucchini, and toss them about to coat with oil. Then cover the skillet, lower the heat, and let the vegetables sweat until tender -- 4-5 minutes.
Stir in the green chiles, strained tomatoes (or tomato puree), olives, seasonings, black beans, and cilantro. Bring the mixture to a simmer over high heat. Then lower the heat, cover the skillet, and let the mixture simmer quietly for 5 minutes.
Preheat the oven to 400°F. Also, lightly grease a 9-12 (or 9x-13) baking dish. Arrange 6 corn tortillas in the dish, overlapping them as necessary. Spread the tortillas with half of the vegetable mixture, and then sprinkle on the cup of Monterey Jack cheese. Then layer on the remaining tortillas, and top them with the remaining vegetable mixture and the cup of Cheddar cheese.
Bake in the preheated oven until the cheese melts -- 15 to 20 minutes. Let cool for 15-30 minutes before slicing into 8 squares. Top each serving with a dollop of sour dream and a sprinkling of cilantro.