Spicy Mongolian Beef

The night before we left for Dresden, I wanted to make something quick, simple, and satisfying. I didn't want to make anything too big, as I hate having leftovers in the fridge over a long weekend. I've been trying for awhile now to break away from my Italian roots, and when I saw this dish on All Recipes, it seemed like the perfect thing to make on a weeknight when I was trying to do a million other things. It was incredibly simple-all you have to do is make the marinade (which took approx. 5 minutes), slice up the flank steak and toss it in the marinade, and refrigerate it for at least an hour before cooking everything. I loved the spicy flavor, although I cut back on the crushed red pepper (1 tablespoon seemed to be a bit much, even for me). This dish received a sound approval from Will, who requested that I make it again.
Source: All Recipes

Ingredients:
1/4 cup soy sauce (I used low sodium)
1 T hoisin sauce
1 T sesame oil
2 tsp white sugar
1 T minced garlic
1 T red pepper flakes (I used 1 tsp)
1 lb beef flank steak, thinly sliced
1 T peanut oil
3 green onions, sliced (I used 1/4 cup white onions)

Directions:

1. Whisk together soy sauce, hoisin sauce, sesame oil, sugar, garlic, and red pepper flakes in a bowl. Toss beef with marinade, cover, and refrigerate 1 hour to overnight.
2. Heat peanut oil in a wok or large, nonstick skillet over high heat. Add the green onions, and cook for 5 to 10 seconds before stirring in the beef. Cook and stir until the beef is no longer pink and is beginning to brown, about 5 minutes.