I am a former chef and I use to rub some oil on it and seasoning very lightly, it will burn if to heavy, then like a beef steak mark it on the grill, moving and turning it as to your liking for doneness, for a piece like that say 2-3 minute on each side for medium rare and for well done 4-5 minutes.
Sauces are your option, I like soya sauce based ones, with ginger, garlic, a few chili peppers or chili oil, sake or rice wine vinegar and a dash of sesame oil, warmed and then cooled to extract the flavours, and just dip away.