Sirloin tip is a misnamed cut, because it does not come from the sirloin primal but from the round primal. (The round is the largest primal, so there's lots of cuts that come from it.)

It's the triangular end of the top round, near the sirloin, which is, I guess, where it gets its name from.

Here's some more information on it: Sirloin Tip Roast

Although it is considered one of the leaner cuts, there's a cap on it that isn't always taken off. There are also a couple of veins of fat and gristle present, sometimes fairly thick ones. I don't buy it very often, but when I do I usually cut it into smaller steaks or stewing beef pieces. Thick pieces of lean beef tend to be harder to get tender than thinner or smaller ones.

If cooking it whole, it does best with lower heat and a longer cook time, but it also does well if braised. Slicing it across the grain means that every slice has some of that fat/gristle in it. Slicing it with the grain is harder to do, but you can rotate it and get something closer to a cross-grain cut.

I've got a couple of books on meat identification and meat cutting on my shelf, this is one that the FFA has on its list of material students use in preparing for meat grading exams: Meat book I think it is a print-on-demand book, and used copies don't show up very often.

Sirloin Tip is the IMPS 167 cut (parts A-F), additional information can be found here:
USDA IMPS

I grew up in a small town where the local butcher raised his own beef and pork, so he knew everything there was to know about the meat he was selling.

Then when we were first married and living in Chicago, there was Fine's on Morse Ave, where you'd tell the butcher what you wanted to make and he'd tell you what cut to get and how to cook it. (There was also an excellent kosher butcher a block away.)

When we moved to Lincoln, there were two stores with good meat departments. I think their quality declined over the years. (One store burned down a few years ago, the other is still there but I almost never buy meat from them.) Recently Fareway opened a meat market in Lincoln and several of their countermen appear to know their product fairly well, so I've been buying much of my meat there, even though it's much further away. And I've been experimenting with a few cuts I hadn't previously tried.

I know there are people who love Whole Foods, but I have not been all that impressed by their meat department, either at the Whole Foods in Lincoln or the one in Pittsburgh. One of the best meat sections I've seen in decades is at McGinnis Sisters in Monroeville PA. When I was in Columbus OH a year ago, the meat, poultry and fish markets at the North Market all made me wish I lived nearby. (The poultry market had more kinds of duck than I've ever seen at one time, and I grew up in Hanover IL, the Mallard duck capital of the United States.)

The advent of boxed beef operations has meant that most stores may have a few meat cutters, but none with the expertise I was accustomed to. And if you shop in the evening or on weekends, there might not be anyone in the meat department at all, much less an expert on cuts and how to prepare them. I have been known to ask the countermen at the meat departments of the stores I frequent a question I already know the answer to, just to see how they answer it.

I have been misled by the sirloin tip cut and a few others myself, and that's why I started studying meat cuts and meat cutting. Not that I'm likely to buy my own side of beef and butcher it, or even 10-20 pound sub-primals very often, but I want to be able to recognize the cuts by their appearance rather than from the label, and know what to do with one before I buy it.

Some of the best information out there can be found by searching for 'FFA Meat Judging', those high school students need to know the major retail cuts and how to cook them. That's not the same thing as a meat cookbook, but I haven't looked at what's available to have an opinion on recent books on cooking meat. I know I still have a lot to learn, I think the average FFA meat judging competitor would run circles around me.

Thanks for the FFA tip Mike. I wish I'd found that when I was at Whole Foods. When we were growing up we would go to the stock yards in Chicago and tromp around with my dad. We learned about different types of cattle and pigs but not much about cuts of meat. If my dad's dad had been alive he might have been able to teach us as he worked at the stock yards cutting and packing meat.

Whole Foods is hit or miss. There are two in my town and there are some very knowledgeable people behind the meat counters. And then there are some people who do not know very much. Of the people who do not know much there are those that readily admit and will find you someone who knows more or there are those who just want to fill your order and move on to the next customer. I knew almost nothing when I started and would go home and study at night to do a better job. There is a fellow I am friendly with at one of the butcher counters and he worked his way up to the meat department. He started out bagging groceries and gathering carts. He's learning and he's smart but he does not have a depth of experience.

We have another meat store that I may try but they are not as convenient as Whole Foods and as long as I do some research before I buy I am usually okay.

Fish is even more complicated because there are at least two schools of thought on how to properly farm fish but that is another story.

I have chef friends here who help me. If you know some good chefs who know their stuff they will usually help. I am about to embark on making my own corned beef and pastrami. I've found some good info on the website AmazingRibs.Com. There is a lot about a lot here and it's not well organized but it seems to have some good info and it is entertaining. For example, he needs to know the difference between a blog post and a recipe!