Preheat oven to 350ºF.

Cook ground beef with diced onion over medium heat until meat is browned. Add taco seasoning to the meat along with the water. Let simmer until it thickens. Add taco sauce, mix to combine. Then remove from heat and set aside.

Mix 2 cups of the cheese and the sour cream. Add green chilis. Set aside until you are ready to assemble.

Grease a baking pan. Add a small amount of enchilada sauce to the bottom of the pan to prevent sticking. Put a layer of the tortillas down in the pan. Add 1/3 of the meat mixture and some more of the enchilada sauce on top of the meat. Top with another layer of tortillas.

Add a half of the green chili and cheese mixture to the top of the tortillas. Add another layer of tortillas and repeat with a layer of the meat, enchilada sauce, tortillas, cheese mixture. The top layer should be just enchilada sauce and the remaining 1/2 cup of cheese.

Bake for about 30 minutes until golden brown and bubbly.