Grill tenderloin over medium heat, or about 4 inches from heat source. Turning several times and basting with reserved marinade mixture, cook approximately 20 - 25 minutes.
Add onion, oranges and mango pieces to the grill. Cook about 5 - 10 minutes, turning occasionally.
Remove beef, fruit and onion to a platter and tent with foil for 5 - 10 minutes. This will produce a medium rare tenderloin.
Serving Suggestion: Slice beef and serve with grilled mango and onion, accompanied by basmati rice. Squeeze the juice from the grilled oranges over top.
Note: Any tender cut of beef (grilling steaks) can be substituted for the tenderloin in this recipe. Adjust cooking times accordingly.