Toast sesame seed in a 350° oven 10 minutes; pulverize in a blender until very fine or crush in a mortar and pestle; place in a small bowl.
Slice round steak into four long strips, each about 3/8 inch thick.
Mix together the soy, Sherry, oil, onion, ginger, and garlic, and let meat marinate for 30 minutes.
Thread on skewers in serpentine fashion (weave in and out on strip of meat lengthwise).
Peel papaya, halve, and remove seeds; cut in sixths.
Peel back a 1-inch strip on each banana.
Peel pineapple, halve, and cut in long slices.
Puree chutney in a blender or chop finely; brush on fruit.
Arrange fruit and meat on tray at table.
To cook, barbecue meat over hot coals, turning once (allow about 5 minutes to a side, or until meat is browned).
Sprinkle lightly with toasted sesame seed.
Meanwhile, skewer fruit lengthwise with bamboo sticks; place on barbecue along with meat (banana should have peeled side down) to heat through and brown slightly.