AKA Boxers Droppers. Again, sorry, no pics. I inhaled it too quick and oh fuck it I'm just gonna come out and say I feel like taking a picture of my food that I made and thinking "This'll look great on my blog" would make me worse than Hitler. You know what steak and mashed potatoes look like. Just imagine that.
First: a note about selecting steaks. Unless you're going super cheap, it makes absolutely no sense to buy any cut of steak other than a T-Bone. It's a NY Strip and a Filet Mignon together, but for the price of a ribeye. If you're just cooking for yourself (and maybe a few other people) on the stove and not the grill, don't bother going to the butcher to get the overpriced ones that are like six inches thick, it's not worth it. Just go to the grocery store, go to the meat section, and make sure you get one where the loin (strip) and the tenderloin (filet) are as equal-sized as possible. The loin's always gonna be bigger, but the tenderloin is really the star of the steak. There's no point in getting one where the tenderloin is like an inch wide (seriously I saw one like that when I was shopping today and laughed in its stupid face).
Second: potato selection. I use red skin potatoes for everything. They're good for French fries, roasted potatoes, mashed, hash, whatever. Most people like Russets for French fries because you get the longer ones and I guess the starch content is a little lower than reds; but the starch difference is minimal and anything you have to fold to get in your face hole that isn't pizza is fucking stupid anyway. Just use reds.
Oh just shut up already and gimme the fucking recipe: the direction in which you cut your steak matters a lot. If you cut along the muscle fibers, it's gonna be harder to chew as you have to break the strands apart and even a filet mignon is gonna be tougher to eat than it has to be. For T-Bones, what you do is position the steak so the T is right side up, and cut thin slices horizontally, starting at the bottom and moving your way up. This way, not only will it be more tender because you'll just be breaking muscle fiber strands apart from each other rather than breaking up a smaller number of longer strands, but each piece on the NY Strip side will have a nice, small piece of fat for you to chew on and get some extra flavor out of but you won't have any pieces that are all fat/gristle.
1 T-Bone (AKA Porterhouse) steak
2-3 teaspoons of Kosher salt
1/2 teaspoon of black pepper
1/2 teaspoon of sugar
1/2 teaspoon of your favorite spice mix (I use Kroger "Zesty" mix)
1/2 teaspoon of this weird espresso rub we somehow have in the cupboard (or, if spices don't magically appear in yours and you can't find an espresso rub, just use some espresso or even regular finely ground coffee and maybe mix in a tiny bit of garlic powder as that was the only other thing on the ingredient list that stuck out at me)
1 stick (8 tablespoons, although you might not have to use the whole thing) of butter
4-5 red skin potatoes (about the equivalent of 4 big ones, so the smaller they are the more you need to use)
3 cloves of garlic
1-2 tablespoons of vegetable oil (don't sub in olive oil or any other stupid shit, veggie oil is perfect because it has a high smoke point and doesn't flavor the stuff you cook in it)
2 tablespoons of Parmesan cheese
1/4 cup of milk
About an hour-hour and a half before you're going to start cooking, unwrap the steak and very liberally salt both sides, patting it into the steak as you go. Leave it on a plate covered in Saran wrap and let it get to about room temperature, or pretty close. When you're ready to go, mix up the other spices, pat the steak dry on both sides with paper towel, and season the steak, patting it in to get it to stick really well.
Skin the garlic and potatoes, chop the potatoes to about 1/4-1/2 inch pieces (smaller is better as they'll cook faster), and either chop the garlic really finely or just microplane it. Start a pot of salted water on the stove to boil. If your broiler is underneath the oven, start it going; if the broiler is in the top part of the oven, move a rack to about the second highest position and start pre-heating the oven by setting it as high as you can, and then turning it off and turning on the broiler right before the steak goes in.
In a cast iron pan, melt about 1-1 1/2 tablespoons of butter over medium-low heat and cook the garlic for about 2-3 minutes, moving it around often to make sure it doesn't burn. Set the garlic aside, add another 1/2 tablespoon of butter and about a tablespoon or 2 of vegetable oil to the pan, and turn it up to high. When the butter fully melts, swirl the pan around to get an even mix of butter and oil, and leave the pan turned about 180 degrees from where you started it, as cast iron retains heat really well but it doesn't heat as evenly as everyone seems to think it does. When the water starts fully boiling, add the potatoes. When you see tiny whisps of smoke coming off the oil in the cast iron pan, lay the steak in and cook it for about 2 minutes on each side. When both sides are seared, flip the steak one more time and put the pan in the oven under the broiler for another 2-3 minutes or so (depending on how well done you want it, but if you intentionally cook it any more than medium I'll come to your house and slap the shit out of you). If you don't have a cast iron pan, transfer the steak into a roasting pan big enough to lay the steak in flat. If you have to use a roasting pan, put it in the oven while it pre-heats so you're not laying the steak into something cold that won't heat up sufficiently in the short time the steak's cooking in the oven.
Once the steak is in the broiler, start checking the potatoes to see if a fork can make it through one of the bigger pieces with little or no resistance. Once you get there, drain the water out and transfer the potatoes to a bowl. If you don't have a potato masher but you do have a blender, you can pulse them at medium/high speed until it's smooth but with a few small chunks still in there so it's not a complete paste. At this point the steak will probably be ready to come out of the oven so get it on a plate with foil over it to let the steak rest so the juices redistribute. Cut the remaining 5-6 tablespoons of butter into roughly 1-tablespoon slices and put them in a bowl with the milk; then microwave it to melt the butter on high for about 30 seconds. If it hasn't all melted after that, don't worry too much; you just want it so that the butter and milk aren't so cold that they affect the temperature of the mashed potatoes too much.
While the steak rests; add the milk/butter, garlic, Parmesan, and salt and pepper to taste to wherever you put the potatoes. Mash/blend the potatoes to your desired consistency, making sure to mix them around so that it all stays even in texture. When it's all good and mashed to your liking; plate everything, serve and enjoy.