Make Gyro Meat (Bake in the morning or day before, if possible): Add onion and garlic to a food processor and very finely chop. Add to a bowl along with the ground meat, salt, pepper, bread crumbs, oregano, cumin, and Aleppo pepper. Use clean hands (or wear gloves if desired) to mix and mash the meat together really well, so it holds together densely.

Bake: Press meat mixture into a 9x5 inch loaf pan. Bake at 325 degrees F for about 50-60 minutes, or until the center registers 165 degrees on a thermometer. Set aside to rest for 20 minutes, and then, ideally, if time permits, refrigerate for a few hours or overnight. (Refrigeration will make the meat much easier to slice.)

Slice Meat: Remove meat from pan (reserve the fat drippings) and cut into thin strips, about 1/8 inch thick.

Brown meat: Heat a griddle, cast iron or skillet over medium high heat. Add some of the meat drippings or a little oil to lightly coat the bottom of the pan. Once hot, lay the meat slices flat in the hot pan and cook for just 1-2 minutes on each side, until browned and crisp. (Alternately, you can lay the pieces flat on a lined baking sheet and broil for a few minutes in the oven.)

Assemble Gyros: Serve gyro meat in a warm pita, topped with tomato, onion, lettuce, tzatziki, and feta.