Sirloin is readily available in the meat section, but for a thicker portion, such as the one called for in this recipe, check with your butcher to see if you'll need to preorder it.
It's extremely important to use the exact thickness and weight of steak called for in this recipe. I've only made this once and the sirloin steak that I bought wasn't quite as thick or heavy as the recipe requires. Thus, I had to flip the steak over halfway through the broiling process and only had to bake for 10 min. Even with those alterations I still had a steak that was well done.
