In a small bowl combine the orange juice, lime juice, cilantro, garlic, and seasonings. Stir together. Will be thick.
Coat the meat in the marinade. Place on a tray, in a bag, or container. Top with orange slices and onion. Cover and refrigerate for 4-24 hours.
Preheat grill to 400°F. Remove the extra oranges and onion from the meat. Grill for 3-5 minutes. Then turn and cook the other side an additonal 3-5 minutes.
Check the temperature of the meat in the thickest part. Rare: 115℉ -120℉ Medium Rare: 120℉ - 125℉ Medium: 130℉-135℉ Well Done: 140℉ - 145℉.
Remove the meat from the grill when desired temperature is reached. Cover with foil and let rest for 10 minutes before slicing.
Slice meat thinly against the grain and serve.
