The site I originally found this recipe on is long gone, but I've substantially changed the spice amounts, made some substitutions, and have definitely greatly changed the technique so I'm claiming this as my own now. LOL
2 lbs ground lamb or a mix of lamb and ground beef (which is what we did, mostly lamb though)
1 medium white onion
4 cloves of fresh garlic, finely chopped
1/2 tablespoon dried ground basil(the original recipe I found called for marjoram, but I don't like)
1/2 tablespoon dried ground rosemary
1/2 tablespoon dried oregano
1 teaspoon fresh grated lemon peel (original used dried, just eww)
2 teaspoons sea salt
1/2 teaspoon crushed red pepper (3/4 to 1 tsp if you like it spicy)
1 teaspoon white pepper
Quarter the onion and place in a food processor with the garlic, pulse several times, scraping down, until very finely chopped. Remove the onion and the garlic from the food processor and wrap in a clean towel (no fabric softener) or piece of cheesecloth and squeeze to remove the liquid. Put the onion/garlic mixture back in the food processor.
Grind spices to a fine powder in a spice grinder. Add the spice mixture and other ingredients to the food processor and let it run until everything is mixed thoroughly, about 2 minutes. Scrape down from time to time. You may have to pre-mix all the ingredients in a large bowl and process smaller amounts individually. The meat mixture needs to be very finely chopped to where it creates a seasoned meat paste.
At this point, you can take a small piece and pan fry until done, taste and adjust seasoning to your liking.
Remove the mixture from the food processor bowl and place on 2 layered pieces of plastic wrap 14-16 inches long, with the long side facing you. Form the meat mix into a roll about 6-7 inches long and start to roll at the edge of the plastic wrap. Twist the long ends to close. To keep it from popping open along the seam, wrap it again the opposite way, with short end facing you. I then did another long way wrap with doubled plastic. Or, you can just use layered cheesecloth. It would probably be easier to compress in the cheesecloth in the next step since it will let air out as you tighten it down.
Once wrapped to where nothing will escape, twist 1 end to close tightly, then stand it up on the closed end, and start twisting/squeezing the other until the meat paste is firm and compacted (like a sausage).
Let the loaf set up overnight in the fridge. Then, remove the plastic wrap and re-wrap in heavy duty foil. Place in the freezer for 2 hours before cooking.
For cooking, build a 1-zone fire with medium heat. The charcoal caddies for the Webber come in handy so the coals can be easily moved later. When the fire is ready, take the meat out of the freezer and place the log on your rotisserie spit, centered and with forks set opposite each other. Place your charcoal caddy directly under the meat for about 30 minutes. After the 30 minutes, move the charcoal caddy off to one side. Remove the foil from the loaf. You want to brown the outside and give it a nice crispy crust. Try to keep the top on as much as possible to keep the heat in. Pull the loaf at at 145-150. Let it rest for 15 minutes or so lightly tented. It will continue to cook as it stands.
Some people that don't have a rotisserie have cooked this in the oven on a rack, then used the broiler to crisp and nicely brown the outside. We've never tried it this way but they seemed to do well with it. Just be sure not to let the internal temperature go past 145-150 because any higher than that will cause the meat to overcook and be dry after standing. You will also need to watch extremely closely and turn frequently once you put it under the broiler so that it doesn't burn.
Serve on pitas or flat breads with your favorite tzatziki sauce, feta, sliced tomatoes, lettuce, whatever you want. I like to add ground cumin into the dough of the flatbread when I make it for a gyro. You can find my recipe for flatbread here.