Prepare vegetables by chopping and mincing. To save time, consider putting the onion, bell pepper, garlic and jalapeno in the food processor and pulse 3-5 times until chopped.
In a small bowl mix together enchilada sauce, sour cream, and 1/2 cup of Mexican shredded cheese.
Steam onions, bell pepper, and jalapeno pepper for 3-4 minutes until slightly tender. You can skip this step if you want to keep a little crunch in your vegetables.
In a large bowl, mix onions, bell pepper, jalapeno pepper, zucchini, garlic, black beans, corn, salt, black pepper, garlic powder, and cumin.
Layer 1/2 sauce mixture on the bottom of a 9 x 13" pan. Add 6 corn tortillas for the next layer. Add 1/2 of the veggie mixture. Repeat sauce, tortillas, then veggies. Lastly add one more layer of tortillas to the top. Finish with the remaining 1/2 cup Mexican cheese.
Bake at 350 F for 40 minutes or until hot and bubbly.