Mexican Lasagna

1 lb ground beef
1 pkg. taco seasoning, reserving 1 Tbs seasoning
1/2 red onion, chopped
1 (15 oz) can black beans, drained
1 (14 oz) can diced tomatoes
1 cup frozen corn
salt
1 cup sour cream, mixed with the remaining taco seasoning
8 flour tortillas (I think whole wheat tortillas taste best with this recipe)
2 1/2 cups shredded cheddar or shredded pepper jack cheese

Brown ground beef and onions and drain
Add to beef: taco seasoning, tomatoes, black beans and corn.
Heat through, 2-3 minutes.
Coat a shallow baking dish with olive oil.
Cut tortillas in half or quarters.
Build lasagna in layers of tortillas, meat, sour cream and cheese, Repeat ending with cheese on top.
Bake at 425 degrees for 12-15 min.
Top with your favorite toppings such as chopped tomatoes, sliced olives, avocado, and/or shredded lettuce (or just put nothing, like I do.)