Bake the pie crust for 5 minutes at 350 degrees. Brown the ground beef and drain in a medium skillet. Add the taco seasoning, onion and water to the beef. Cook for 5 minutes, stirring occasionally. Mix the egg, sour cream, milk and salt together in a large bowl. Drain the tomatoes and add to the beef mixture. Add the bell pepper and black olives to the beef mixture. Mix lightly. Spread the ground beef mixture in the pie crust. Top evenly with the sour cream mixture and sprinkle with the cheese. Place the pie pan on a cookie sheet and bake at 350 degrees for 50 minutes. Cool for 15 minutes and cut into wedges to serve.