Lime Sour Cream Instructions:
In a bowl, whisk together sour cream, lime zest and juice; season with salt to taste.
Cover and refrigerate until ready to use.
Using a chef’s knife, thinly slice steak crosswise into thin strips.
Toss with chili powder, cumin, salt and pepper.
In a non-stick skillet, heat half of the butter over medium high heat and brown the beef. Remove to plate.
In the same skillet, add remaining butter and sauté onion, bell peppers and cilantro for 4 minutes or until tender crisp.
Return beef to skillet and heat through.
Divide mixture among tortillas and top with lime sour cream.