Prepare grill. Cut steak into 1/8-inch strips.
To make marinade, in small bowl, whisk together 1/2 cup dressing, the brown sugar, 1 tablespoon cilantro and the gingerroot.
In large, shallow nonaluminum baking dish or plastic bag, combine 1/4 cup marinade and the steak; turn to coat. Cover dish or seal bag; marinate in refrigerator, turning occasionally, 2 hours. Refrigerate remaining marinade. Meanwhile, in small bowl, blend together peanut butter, 1/2 cup dressing, the curry powder and cayenne.
Remove steak from marinade; discard marinade. Thread steak on skewers. Grill steak, turning once and brushing frequently with refrigerated marinade, 2 minutes or until steak is desired doneness. Serve with peanut sauce and, if desired, Cucumber Relish.
To make relish, in small bowl, combine cucumber, onion and remaining 1/4 cup dressing and 1 tablespoon cilantro; refrigerate.
This recipe is recommended for 4 servings.