Separate the white part of the green onions from the green part.
Place the green parts of the green onions in a small bowl, cover, and refrigerate until serving.
In a medium bowl, whisk together the sliced yellow onion, white parts of the green onion, and all the remaining ingredients except for the steak and set aside.
Very thinly slice the steak using a sharp knife.
Add the steak slices to the marinade, stir, and cover.
Let marinate in the refrigerator for at least 2 hours or as much as a day.
Heat a large skillet over medium high heat.
Cook the steak in a single layer in batches for best flavor. The goal is to sear and caramelize the steak without letting it steam. Cook for 4-5 minutes, flipping halfway, or until just cooked (do not overcook!).
Garnish with the reserved green onions and serve.
Cook the steak on the grill by threading the strips onto skewers.