1. Preheat your oven to 350 degrees, and preheat a medium-sized pot at medium heat on the burner. Chop the onion and garlic cloves.
2. Put a tablespoon of butter in the preheated pan, then add the onion and garlic. Cook, stirring occasionally, until they soften.
3. Add the can of tomatoes and taco seasoning. Mix well.
4. In a separate pan, brown the veggie crumbles/ground meat. If you're using veggie crumbles, you don't have to heat them too much. They will also cook in the oven, and can get mushy if they're over-cooked.
5. Add the frozen corn/black bean mixture to the onion/garlic/tomato pot and mix well.
6. After the corn/black bean mixture has been thoroughly heated, remove the pot from the burner. Finish browning the veggie crumbles/ground meat, and add to the vegetables.
7. Put the tortillas in the pan you want to cook the lasagna in, and trim them to fit. Save the excess; you may need it to fill in later.
8. Put one cup of the vegetable/"meat" mixture in the bottom of the pan and spread it out. Add two layers of tortillas, two more cups of the vegetable/"meat" mixture, and a generous handful of cheese. Continue these layers until you run out of ingredients.
9. Place the pan in the oven and bake for about 30 minutes, until the cheese is melted and the sauce is bubbling. If you don't want to wait, that's okay - all of the ingredients are already cooked, so you can just heat it up until the cheese melts. Enjoy!