½ of an avocado, seeded, peeled, and chopped (optional)
¼ cup snipped fresh cilantro (optional)
In a medium bowl, combine garlic powder, cumin, paprika, and cayenne pepper. Add steak strips and toss to coat. Coat an unheated 4-quart nonstick Dutch oven with cooking spray. Heat over medium-high heat. Add half of the steak strips. Cook for 2 to 4 minutes or until browned, stirring occasionally. Remove meat from the pan and repeat with remaining steak strips.
Add the oil to the Dutch oven. Add sweet peppers and onion. Cook over medium heat for 5 minutes or until lightly browned and just tender, stirring occasionally. Add broth and undrained tomatoes. Bring to boiling. Stir in steak strips and heat through.
To serve, ladle soup into bowls; add a dollop of sour cream and sprinkle with lime peel and tortilla chips. If desired, top with avocado and cilantro.
Tip: Partially freeze beef about 30 minutes for easier slicing into strips.