Step 1Heat the olive oil in a wide skillet over medium heat and cook the onion just until softened, about 4 minutes. Meanwhile, remove the seed pods from the poblano chiles by cutting around the stems. Cut the chiles into strips and dice. Add them to the onion and continue to cook. After 5 minutes, add the bell pepper, corn and zucchini. Cook until the zucchini is tender, a couple of minutes longer. Season with salt and pepper to taste. Set aside.
Step 1Combine the onion, tomatoes, jalapenos and cilantro. Season with the chile powder and salt.
Step 1Drain off any excess liquid from the black beans and roughly puree them in a food processor. Set aside.
Step 2Oil a 15x10-inch jellyroll pan. Heat the oven to 350 degrees.
Step 3Lay out the first tortilla in the middle of the baking dish. Spread on a thin layer of pureed black beans, about 1/2 cup. Next add a layer of sauteed vegetables, about 1/2 cup of grated cheese and a layer of salsa. Repeat layering. As you build, lightly press in the middle. The torta tends to bunch up in the middle. Don't press too hard or overwork when spreading. Just lightly spread on each layer. Finish with the sixth tortilla, spread on the last layer of beans, a layer of salsa and 1 cup of cheese.
Step 4Bake until the cheese is bubbly and beginning to brown, about 35 minutes. Allow the torta to rest about 15 minutes before serving.