Combine oregano, cumin, garlic powder, onion powder, cayenne, salt and pepper, and avocado oil in a large zip top bag. Add steak and knead to mix. Refrigerate 20 minutes.
Preheat grill. Grill steak over medium heat 4 minutes per side or until it has reached desired doneness. Let rest 5 minutes before cutting. Dice.
Soup: Slow Cooker
Prepare steak as directed. Add steak and all remaining ingredients, except cheese and green onions, in a slow cooker. Cook on low 4 hours or on high 2 hours. Stir in cheese and serve topped with green onions.
Soup: Instant Pot
Prepare steak as directed. Add steak and all remaining ingredients except cheese and green onions to Instant Pot. Lock lid; set valve to sealing. Program for soup. Allow for natural pressure release.
To Freeze
Prepare steak as directed. Add steak and all remaining ingredients, except cheese and green onions, to a freezer bag. Freeze.
To Cook After Freezing: Slow Cooker
Add frozen meal to slow cooker. Cook on low 6 hours or on high 4 hours. Stir in cheese and top with green onions.
To Cook After Freezing: Instant Pot
Add frozen meal to Instant Pot. Press sauté. Allow to heat long enough for 1/2 to 1 cup liquid to accumulate at the bottom. Lock lid; set valve to sealing. Program for soup. Allow for natural pressure release.