SCORE steak diagonally across grain at 3/4-inch intervals.
COMBINE oil and next 7 ingredients in a shallow dish or heavy-duty zip-top plastic bag; add steak. Cover or seal, and chill 8 hours, turning occasionally.
REMOVE steak from marinade, reserving marinade.
GRILL steak, covered with grill lid, over high heat (400 to 500 degrees) about 6 minutes on each side or until desired degree of doneness.
BRING reserved marinade to a boil in a saucepan, and boil at least 1 minute or until reduced by one-third.
STIR together cornstarch and 3 tablespoons water until smooth.
Add to marinade; bring to a boil over medium heat, stirring constantly. Boil, stirring constantly, 1 minute; remove from heat. Spoon over steak.