Finely zest and juice 1 orange. Combine with marmalade, syrup, mustard, ginger, garlic, salt and white pepper in a shallow ceramic dish. Add steaks and turn to coat. Cover, refrigerate and marinate for at least 1 hour or overnight.
Heat a chargrill pan or barbecue grill over medium heat. Cut remaining oranges into wedges. Remove pork from marinade, reserving marinade. Cook pork and orange wedges for 4 minutes on each side or until lightly charred and cooked through.
Meanwhile, cook marinade in a small pan over medium heat. Bring to the boil and simmer for 3 minutes.
Pour sauce over pork, if using a chargrill pan, and cook for a further 1 minute to glaze, or brush sauce on occasionally, if barbecuing.
Combine cashews and parsley and serve with pork and oranges.