Slice your meat in thin strips and toss in a Ziploc bag with cornstarch. Add all of the liquid and dried spices to your crockpot and mix well. Add the minced garlic and three of the sliced green onions. If you are using fresh onion dice very small and add that now, too. (That can be replaced with 1 teaspoon dried minced onion.) Put your meat on top, and toss gingerly to coat. Cover and cook on low for 4-6 hours. Flank steak is thin and have very little fat, and will cook quickly. There isn’t a lot of liquid in this dish, so if your crock tends to cook hot, please check it after 3 hours. The meat is done when it is no longer pink and has reached desired tenderness.