Preheat oven to 425 degrees F and spray a 9x13 inch casserole dish with non-stick spray.
Make the meat mixture: preheat a large skillet on the stove over medium high heat. Add the ground beef and onion and cook until meat is cooked through and onions are tender.
Drain excess grease.
To the meat add in 1 packet taco seasoning, 2 cups salsa, ⅓ cup water, and ¼ cup taco sauce.
Add in 1- 15 ounce can corn that has been drained, along with 1 and ½ cups cooked rice. Simmer for 5-6 minutes.
Assemble the Mexican Lasagna: pour half of the meat mixture on the bottom of the casserole dish. Top with a layer of tortillas. Spread half of the cheese on top of the meat mixture. Add remaining meat mixture on top of the cheese, then add another layer or tortillas and top with the remaining cheese.
Bake for 15 minutes or until cheese is melted and bubbly.
Garnish with tomatoes, green onions, sour cream, and taco sauce or enchilada sauce.