Whisk molassas, vinegar, oil, and pepper sauce together in a bowl. Place flank rolls in bowl or plastic bag with marinade; cover or seal and store in refridgerator for 2-3 hours.
If using bamboo skewers, soak skewers in water for 15 minutes. Remove beef from marinade, unroll and cut to 3-4" strips. Push skewers through beef. Grill or broil for 7-10 minutes turning once.