Pictured: Roast lamb. Not shown: me drooling all over the silverware.
I'm breaking from tradition here for a bit, but bear with me. There's a reason. Gyros, for the record, are one of my favorite foods. It's a greek taco, where's the bad? Real gyros, contrary to popular belief, could be made of any meat, for the most part. They came about in the 19th century as an offshoot of turkish standing rotisserie fare, and were created after beef was introduced. Pork and chicken are fairly common, as well. I'm pretty sure the only meat that isn't used for a gyro is fish, or at least if it is, I'm not aware of it.
Traditionally, a gyro was a piece of meat, lightly seasoned, roasted on a vertical spit until basically falling off the bone. Well, I don't know about you, but I don't have a vertical spit, and I'm sure as hell not about to build one or the fire big enough to heat the meat, so we're going to improvise. Our improvisation is not going to be the "make a meatloaf!" option that even culinary super-heroes like Alton Brown tend to suggest. No, we're going to slow roast this thing. It'll be a long roast, but low heat so I'm not going to bake you out of your house. I suppose you could also do this on a bbq, rather easily. You'll want a pan to catch the drippings, though, because you can make a hell of a sauce by just dropping a bit of cream into it, then adding some tomato sauce and reducing it. I freeze the stuff for later lamb gravies and such, too.
As well as not feeling like mucking about with the standing rotisserie, I find the traditional american gyro to be a bit bland. plain tomatoes, iceberg lettuce, they usually use white onions. I say no. Let's go mediterranean. Gyros are greek, greece is on the mediterranean, so let's go all out. This one is a three parter. Sorry about that, I hate doing combo recipes but you kinda have to have the sauce too, and well... We have to put the thing together, right?
ROAST LAMB
lamb shoulder (maybe 3 lbs)
sliced red onion
2 cloves garlic
~2 tblsp fresh cracked pepper
~1 tblsp cumin
So, take your lamb shoulder and cut off a bunch of the fat. I know, somewhere in the back of your head there's a small angry chef yelling some complex formula about how the fat will render and blablabla. Smack him, he's wrong. Only so much fat will render into the meat, and lamb is a really fatty meat. The marbling alone will do it, along with whatever little bits you miss. I really suggest doing the same with all slow roasted meat, since you don't need a huge amount of fat to get tender meat, snd it's easier to cut it off fresh rather than pull it out when it's cooked.
Preheat a skillet on medium-high, and put a bit of oil in it. You'll want something that can take heat, like canola. No olive oil, it burns too easy. Also, preheat your oven for like 225 or so. Real low heat. Mince the garlic, and stab the meat a few times, stuffing bits of the garlic inside of the meat, and being sure to get a decent distribution. Then, dust the meat evenly (on all sides) with the pepper and cumin, patting it down into the meat a bit. Sear the meat on all of it's sides for about a minute per side, to get that maillard process kicking and toast the herbs a bit.
Put the meat in a big baking pan, being sure to give at least 2 inches of clearance per side. Top it with sliced red onions, cut crosswise rather than straight up and down, and cover the whole thing in aluminium foil or a lid if possible. You want to seal the juices in as best as possible. DO NOT BASTE. Basting actually dries meat out, if you want it to be juicy cover it, and as well basting makes you have to keep opening the oven, which leeches heat. You'll want to cook for about 3 hours. I won't tell a specific time. Instead, grab a thermometer and check the temperature near the thickest part of the meat. You want 150-155 degrees. This works better by temperature than it does by time.
When the meat is done, either grab 2 forks and shred, or cut with a sharp serrated knife to get big semi-thick chunks of meat. You can probably discard the onions, they're pretty well used up by now. For the record, add a bit of fresh chopped rosemary and this makes a hell of a meal in it's own right. See also: the picture.
GARLIC DILL TZATZIKI
1 lb greek yoghurt
1 cucumber, peeled, deseeded, and minced
4 cloves minced garlic
1 tblsp olive oil
2 tblsp balsamic vinegar
1 tblsp fresh dill, chopped (dill weed will work, too, in a nutshell)
You'll want to dry the cukes in a folded paper towel to remove as much moisture as possible. If you don't have greek yoghurt, you can take just the plain stuff and basically put it on a paper towel that you rubber banded over a bowl, and set the bowl in the fridge for about an hour or so. Greek yoghurt is just thicker plain yoghurt, really. After you have those 2 taken care of, just mix it all together, really. Why dill? It's not traditional, but hey. It's in pickles, and dill goes great with yoghurt, not to mention the tiny bit of tang it'll give your gyro.
Assembly
sun dried tomatoes, chopped into strips (you could sub the regular tomatoes, but I suggest the sun dried kind. If you use the regular ones, de-seed and chop them. you'll get more per bite that way and they won't sog up your gyro)
thick crumbled feta cheese
romaine lettuce (bonus points if you tear it rather than chop it)
red onion, chopped into strips
the lamb
the tzatziki sauce
optional: mint leaves
Really, just throw it all on there. Personally, I like to toss all of the veggies together with the tzatziki like a salad and then top the meat with them. It's less messy that way, stuff flies out less, and you get more of a full flavor rather than those big bites of just onion you get at most places.
For the record, that method can be used with just about any big shoulder of meat, complete with the temperature you want to aim for. It aims for medium, which is always safe (those medium well rules? it's a precaution. medium rare is safe if the food is handled properly, medium is always safe, but some undercook a medium) and will universally guarantee a piece of supple, moist meat that falls apart off of the fork, no knives required.