It's not often that you see sirloin on sale for $2 a pound, so I had to take advantage of it. Sirloin is pretty tender as is, which means it's great for short and fast cooking--like stir-frying.
Recipe from
Epicurious.
Ingredients: 1 1/2 tablespoons cornstarch
1/4 teaspoon salt
1/4 teaspoon black pepper
3/4 pound sirloin, sliced against the grain 1/8 inch thick
3 tablespoons vegetable oil
10 ounces frozen broccoli florets, thawed
3 garlic cloves, chopped
3 tablespoons soy sauce
1/3 cup water
Ok, so I missed a bunch of pictures. Cut the sirloin as thin as you can (it's
much easier to do this if you partially freeze the meat by throwing it into the freezer for about 30 minutes, since it'll hold its shape better while you're cutting it), then coat with cornstarch and add seasonings and stuff. And stuff.
Also, prep the broccoli and garlic.

Get the pan hot (like medium-high on the stove), and throw in the sliced sirloin. Let it sit for a bit so that you get that nice brown crust.

Once the sirloin is cooked, set it aside, add some more oil, then add the broccoli and garlic. Stir constantly, because a hot pan + garlic = burnt garlic, and burnt garlic = bad news.
(so hot pan + garlic = bad news by transitivity?)

After about 2 minutes, add the sirloin back in, add the water and soy sauce to deglaze, scrape off all the good bits off the bottom of the pan, and let the liquids reduce to get a good sauce going.
Rather than water, I'm sure you could use something else. Vinegar? Shaohsing wine?

Serve over white rice.