Remove cilantro leaves from stems and chop

Cover and set aside

Peel garlic and trim stem end from chili and cut in half

Place orange juice, chili powder, garlic, serrano chili and olive oil in a blender and puree until smooth

Divide sauce in half and stir half into sour cream; cover and refrigerate

Pour remaining sauce over steak, turning to coat and marinate for 4 hours in the refrigerator

Heat grill and cook steaks, 3 to 4 minutes per side or until cooked to desired doneness

Let stand 5 minutes and cut across the grain into thin strips

Serve topped with Sour Cream Sauce and sprinkled with cilantro.