To a medium bowl add lamb, salt, pepper, oregano and cumin. Mix with your hands until thoroughly combined. Cover and refrigerate 1 hour.
Preheat oven to 300˚F.
Add onion and garlic to the bowl of a food processor and pulse several times to mince; scrape down sides with a rubber spatula. Add lamb mixture and bacon pieces; process to a smooth puree, scraping down sides as necessary.
Line a baking sheet with foil. Transfer meat mixture to center. Wet hands and form meat into a rectangle, approximately 8-inches long, 5-inches wide and 1 1/2-inches high.
Bake 30 to 35 minutes until an instant read thermometer reads 155˚F. Remove from oven and let stand 15 minutes before slicing.
Adjust oven rack to highest position and preheat broiler. Line baking sheet with foil.
Transfer loaf to a cutting board and carefully slice crosswise into 1/8-inch thick slices. Arrange slices on prepared baking sheet, leaving a little room between each one. Broil 2 minutes, until slices are hot and edges are crispy. Remove from oven and tent with foil.
Serving Suggestion: Warm pita bread and spread with a thick layer of tzatziki sauce, pile on gyro meat slices and top with thinly sliced onion and chopped tomato.
Note that nutrition information does not include pita or toppings.
An easy way to warm pita bread is to broil on a baking sheet for 30 to 45 seconds per side.