Adapted from Gourmet
1/4 cup low sodium soy sauce (this is important-make sure you use low sodium or the end result will be too salty)
1 tbsp sugar
2 tsp sesame oil
2 tbsp sake
1 bunch scallions (white and light green parts separate from the dark green, minced)
1 tbsp garlic, minced
1 tbsp fresh ginger, minced
2 tbsp sesame seeds
1 lb flank steak, sliced very thin ( 1/8th of an inch?) across the grain
Mix together the soy sauce, sugar, sesame oil, sake, white and green parts of scallion, garlic, ginger, and sesame seeds in a bowl. Toss with steak strips, cover dish with plastic wrap, and chill for about 2 hours.
Get your frypan hot over medium heat. Add a little oil. Add about half of the beef strips, stirring and moving it around quickly as it sears. The trick with having tender steak strips is to cook it just briefly. When sliced so thin, beef doesn't need long to cook at all-maybe just 1-2 minutes per side. Don't crowd the pan, but rather cook in batches, stirring it around as you go.
Heap the cooked steak strips on a plate, sprinkle the remaining green onion over top, and serve with rice.