Mix thoroughly in a shallow dish the peach syrup, oil, soy sauce, lemon juice, minced onion, salt, pepper, ginger, and garlic.
Add steak pieces and turn until pieces are coated.
Refrigerate at least 2 hours, turning pieces several times.
Remove meat from marinade and drain.
Thread meat pieces on 8-inch skewers alternately with onions and green pepper squares; put kabob pieces close together for rare meat, separate them slightly for well-done meat.
Arrange kabobs on broiler rack and brush with reserved marinade.
Broil with tops of kabobs about 3 inches from source of heat, 7 to 10 minutes, turning kabobs several times; brush frequently with marinade.
Test for doneness by cutting a slit in meat and noting internal color of meat.
During last 3 minutes of cooking, spear a peach half on the end of each skewer, brush with marinade and finish broiling.