Add the beef to the slow cooker. Add the enchilada sauce, salsa, green chiles, garlic, onion, chili powder, cumin and pepper. Stir.
Cover and cook on low for 8 hours.
When the cooking time is done. Cut the corn tortillas into strips, add to the slow cooker along with 1 cup of the cheese and half of the green onions. Stir and flatten out with a spatula. Sprinkle over remaining cheese.
Add the lid back on the slow cooker and continue cooking for 30 more minutes on high. Sprinkle with remaining green onion and tomatoes.