Stir together the enchilada sauce and diced tomatoes in a small bowl and set aside.
Chop all of your vegetables (onion, zucchini, pepper, jalapeño, garlic) and add them to a large mixing bowl. Add the kidney beans and corn to the bowl as well. Sprinkle with salt and pepper and toss to coat.
Spread 1/4 cup of the enchilada sauce/tomato mix evenly onto the bottom of your slow cooker. Add one layer of 3 flour tortillas over top. (I was able to set 2 tortillas side by side and then cut the third in half to cover the leftover space.)
Add 1/2 of the chopped vegetables and 1/4 of the sauce/tomato mixture. Sprinkle with 1/3 of the cheese and then repeat.
Top with one last layer of tortillas, sauce, and cheese. Poke a few holes into the top tortilla with a knife to let some steam escape or else that top layer will puff up as it cooks.
Cover with a lid and cook on low for 4 hours.
Turn to "keep warm" setting until ready to serve.
Serve with chopped cilantro, hot sauce, and sour cream.