Slice the roast against the grain as thin as 1/2 the thickness of a silver dollar. Chop the green onions and set aside. Thinly slice the ginger root. Lay several slices of roast in the bottom of a 11x15-size covered non-metal container. Sprinkle some of the ginger root and green onions on top and continue layering until all the meat, onions and ginger are used. Mix the soy sauce and water and pour over the meat. Seal container tight. Let sit overnight in the refrigerator for at least 24 hours, turning over several times.After sitting for at least 24 hours, uncover the meat and slice it into 2-inch strips. Cut up peppers and onion into chunks. Warm up the grill. Slide and alternate pieces of meat and veggies (peppers, onions, tomatoes, mushrooms, etc.)  onto the sticks to make 15-20 shish kabobs. Place each stick on the grill, turning every few minutes until the meat is cooked. Spoon some sauce over the kabobs while on the grill to keep moist. Serve.