1. Soak 24 bamboo skewers in hot water. Combine maple syrup, 1 teaspoon five-spice powder, vinegar, pepper flakes and soy in large plastic food-storage bag or large glass baking dish. Add flank steak; refrigerate 30 minutes to 1 hour, turning occasionally.
2. Heat broiler. Remove steak from marinade, letting excess drip back into container. Place steak on cutting board. Transfer marinade to saucepan.
3. Slice steak diagonally across grain into 1/4-inch-thick slices. Thread slices onto soaked skewers.
4. Stir cornstarch into reserved marinade in pan. Boil 3 minutes. Reserve half of marinade for serving; use remaining half for cooking.
5. Place half the skewers on broiler-pan rack. Brush lightly with marinade. Broil about 4 inches from heat for 3 minutes. Flip over. Brush again with marinade. Broil additional 3 minutes. Remove to a platter. Repeat with remaining skewers.Spiced Couscous:
6. Meanwhile, bring chicken broth, water, 1/2 teaspoon five-spice powder, raisins, carrot and oil in medium-size saucepan to a boil. Stir in couscous; remove from heat and cover saucepan. Let stand 5 minutes. Fluff with fork. Stir in chopped scallions.
7. Serve the couscous with the meat skewers and the reserved marinade as a sauce.