Cut the steak into 24 (3 by 1-inch) strips, each weighing about 1/2-ounce. Using skewers, stick a skewer into each strip lengthwise and arrange on a large platter or baking pan. Refrigerate until needed.
Prepare the marinade: In a small bowl, combine all the marinade ingredients and pour over the meat, turning to coat all sides. Let marinate, un-refrigerated, about 15 minutes.
Preheat the grill or broiler.
Prepare the sauce: In a small skillet, melt 2 tablespoons butter. Add the garlic and green onion and saute over medium-high heat until soft, about 2 minutes. Pour in the stock, soy sauce, and chile flakes and cook 1 or 2 minutes longer. Strain into a clean pan and whisk in the remaining 4 tablespoons butter. Keep warm.
Arrange the skewers of steak on the grill or under the broiler, being careful that the bare ends of the skewers are not directly over or under the flame. Grill or broil until medium rare, about 30 to 40 seconds per side.
Pour the sauce into a small bowl and set in the center of a large serving platter. Arrange the skewers around the bowl and serve immediately.
**You can also use chicken or lamb for the skewers.