In a large pan, brown your ground meat. When the meat has started to brown in places but is still partially uncooked, add the chopped onions and cook for about 5 minutes, stirring frequently
Add corn, beans, tomatoes, chiles, taco seasoning, and water. Mix well and simmer for 10 minutes, stirring in lime juice as you take it off the heat
Grease a 9x13 baking dish (butter, cooking spray, etc)
Place 1 cup of filling mixture on the bottom of the pan. Place half of the tortillas on top of the ground meat, overlapping and placing them so they come about 1/2 inch up the side of the dish
Spoon half of the remaining filling filling on top of the tortillas, then spread the sour cream over that. Layer the rest of the tortillas, then the rest of the filling. Top with shredded cheese
Place in heated 350°F oven and bake for 25 minutes. Garnish as desired. Let stand for 5 minutes before serving