Slice the Flank Steak (1.5 pound) against the grain into 1/2-inch thick slices with your knife at an angle.
If your steak slices are really long, cut them down into about 3 inch pieces. Pat the pieces of steak dry with a paper towel.
Slice the Scallion (2 bunch) into-2 inch pieces. Separate the 2-inch white pieces from the 2 inch green part.
Slice enough Mini Peppers (1 cup) to make a cup. Mince Garlic (4 clove) and set aside.
In a cup, whisk Water (3/4 cup), Oyster Sauce (2 tablespoon), Lime Juice (2 tablespoon), Crushed Red Pepper Flakes (1/2 teaspoon) and some Salt (to taste) and Ground Black Pepper (to taste).
Add the Corn Starch (1 tablespoon) and mix well until the cornstarch is dissolved.
In a large pan or wok, heat some Ground Black Pepper (to taste) on high. Sear the meat in 2 or 3 batches, so that you don’t overcrowd the pan (it won't sear properly). Season with Salt (to taste) and Vegetable Oil (to taste). Cook for about 2 minutes total, or just until browned and almost cooked through. Set aside.
Add more oil to the pan, along with the scallions whites and garlic.
Add the sliced bell peppers and saute together, for about 1 minute.
Whisk the sauce one more time, and add it to the pan. Cook the sauce, while scraping the bottom of the pan with a wooden spoon or spatula, to pick up the brown bits.
When the sauce comes to a bubble, add the steak back along with the scallions greens.
Toss and cook for 1 minute more. Remove from the heat.
Serve with some White Rice (to taste) and enjoy.