Preheat oven to 325℉. Spray a 9 x 13 inch baking dish with non-stick cooking spray.
Brown ground beef until no longer pink, drain grease. Then add taco seasoning and water and let simmer for 3-4 minutes.
In a medium bowl mix sour cream, mayo, half of the cheese, and half of the onion together and set aside.
In another bowl, mix together biscuit mix and water to make a soft dough. Press dough into the bottom and ½" up the sides of greased 9 x 13 inch pan.
Saute remaining onions and green peppers until barely tender.
On top of the biscuit, layer the remaining ingredients in this order: ground beef, diced tomatoes, green peppers and onions, green chilies, sour cream mixture, and remaining cheddar cheese.
Bake for 30-35 minutes or until edges are slightly browned.
Notes
Try gluten free Bisquick to make this recipe Gluten Free Friendly