Brown meat and onions in a skillet until the meat is no longer pink.
Add the tomato sauce, water and taco seasoning mix and stir well. Let simmer for 10 mins.
While that is cooking, put the tortilla chips in the bottom of a sprayed 13x9 baking dish.
Pour the meat mixture carefully over the chips,do not stir. Sprinkle the cheese over the whole thing and bake at 350 for 20 mins until nice and bubbly.
Sprinkle with the green onions and serve with more chips and sour cream.
VARIATIONS I have tried and love. If you are stretching a budget or feeding a crowd you can add a can of corn or a can of black beans or both to the mixture. If it seems too dry add some salsa or a can of rotel tomatoes. This reheats nicely in the microwave the next day.