Brown the pork in a large skillet over medium heat for about 10 minutes, breaking up the pork as it cooks, until the meat is no longer pink inside. Stir in the onion, green pepper, and garlic, and cook and stir for another 10 minutes, until the onion is translucent. Sprinkle on the taco seasoning, stir to incorporate, then mix in the flour. Stir the mixture, pour in the beef broth, and bring to a boil. Cook and stir the mixture for about 5 more minutes, until it starts to thicken.
Mix in the mushroom soup and milk, bring back to a boil, and add the American cheese. Cook and stir the stroganoff for 5 minutes, until the cheese has melted and the mixture is bubbling. Add salt and pepper to taste, and serve hot.
