You can use any hearty vegetable for this. It cooks pretty quickly, so start some rice first. I was going to take some cool pictures with one of the fancy cameras around here, but I couldn't figure out how to work the dang thing :P so you'll have to use your imagination. Basically it looked like this picture that I ganked from Epicurious, but with lots of tasty beef:
You will need:
1-1.5 lbs beef: tri-tip, blade steak, or flank steak work best
A lot of hearty greens, such as bok choy or broccoli
3-5 shallots or 1 red onion
2 cloves garlic
red pepper flakes
chicken broth or water
Slice the beef into thin, bite-sized strips and coat with with 1 tbsp fish sauce, 1 tsp brown sugar, 1/2 tsp white pepper, and 1/2 tsp ground coriander. Allow to sit for at least 15 minutes.
If you're using bok choy, slice the larger specimens into quarters and the smaller ones in half, lengthwise. Clean as thoroughly as possible, to get any grit out from between the leaves.
Peel the shallots and chop each one only once or twice, so it's in nice big pieces. Mince the garlic finely. In a small dish, combine soy sauce, fish sauce, vinegar, sesame oil, and brown sugar into a sauce that tastes good to you. You will only need about 1/4 c. sauce.
Heat a large, flat-bottomed pan until it juuuuust starts to smoke. Add the meat in 2-3 batches so that it isn't crowded in the pan. Your goal is to cook the meat on both sides on very high heat so that the edges are crisp and brown (1-2 minutes per side). Set the cooked meat aside in a bowl. If the bottom of the pan has a lot of crusty stuff, deglaze it with some broth or water and pour this into the bowl.
Heat up more oil until very hot and add some red pepper flakes. 10 seconds later, add the shallots and garlic and stir until the shallots are softened a bit and the edges are brown. Add half of the bok choy and stir fry 2 minutes. Add the second half of the bok choy, the meat and any drippings from the bowl, and your sauce. Stir well and either leave the pan open to evaporate the liquid while the veggies steam, or put the lid on--it depends on how much liquid you have and how wet you want it. Allow to steam until the veggies are a nice done-ness. The two-stage veggie approach gives you a variety of textures. Serve over fresh rice.