Place meat in a casserole dish. Combine orange juice, lime juice with lime pieces, chili powder and adobo in a small bowl. Pour over steak. Cover and marinate overnight in the refrigerator.
Preheat grill to medium-high. Remove meat from marinade, discarding marinade. Grill for 6 to 7 minutes per side or until meat reaches desired doneness. Remove from heat and let rest for 5 to 10 minutes. Cut meat into 1/2-inch pieces and place in warm tortillas. Serve on a platter with all of the condiments: onion, avocados, tomatoes, sour cream and cilantro.