Grease a 9-inch springform pan with cooking spray or butter and set aside. In a large bowl add all-purpose flour, baking powder, and salt and stir to combine. Cut in the butter until pea-size chunks form, then add in the milk and mix with a fork until a dough comes together. Roll the dough out into a circle and press into the springform pan and up the edges. Refrigerate while you make the beef mixture filling and cheese topping.
In a large skillet, heat 1 tablespoon of vegetable oil and add the lean ground beef, onions, and garlic and cook on medium-high heat until no longer pink. Drain the fat by putting the meat mixture in a colander. Place back in the pan and add chopped green chiles, taco seasoning mix, and water. Cook until most of the liquid has cooked off, about 5 minutes.
In a small bowl combine the sour cream, cheddar cheese, egg, and mayonnaise.
Remove the dish from the fridge and pour the ground beef mixture into the crust. Top with the cheese mixture and bake until set, about 35-45 minutes.
As the easy taco pie cooks, prepare your salsa by combining diced tomatoes, jalapenos, cilantro, and white onion. Season with salt and lime juice. Set aside.
Remove from oven and allow to cool 10 minutes before serving. Serve with the homemade salsa.