Remove outer leaves of the lemon grass. Using a sharp knife, cut one end of each lemon grass piece into a sharp point; set aside. Cut a 1/2-inch slit in center of each green onion piece; set aside. Mince cuttings from lemon grass skewers, and stir together with the five-spice powder and salt.
Rub five-spice powder mixture into beef strips. Cut a 1/2-inch slit every 3/4 inch along beef strips to make three slits.
Thread a beef strip onto a lemon grass skewer through the first slit in the strip; add a green onion piece, then thread beef strip onto skewer through the strip's second slit; add a second green onion piece, and thread beef onto skewer through the third slit. Repeat with remaining skewers, beef strips, and green onion piece, and thread beef onto skewer through the third slit. Repeat with remaining skewers, beef strips, and green onion pieces. Place skewers in a large bowl; add coconut milk to cover. Cover bowl; refrigerate at least 2 hours or overnight. Remove beef skewers from coconut milk.
Grill on an indoor grill according to manufacturer's directions or on rack of uncovered grill directly over medium-hot coals for 6 to 8 minutes for medium doneness, turning once. Serve with Satay Sauce or purchased satay sauce over hot cooked rice, if desired. Makes 4 servings.