Combine salt, oregano, coarsely ground black pepper, cumin, cayenne pepper, and cinnamon in a small bowl and mix thoroughly to make the spice blend.

In a large bowl, mix ground lamb, ground beef, chopped onion, spice blend, minced garlic, and vegetable oil with your hands until evenly distributed. Cover and refrigerate for several hours, then test seasoning by frying a small amount in butter and adjust if needed.

Blanch bacon slices in hot water for 3 minutes, then drain on paper towels.

Line an 8½ x 5 x 3-inch loaf pan with the blanched bacon, covering the bottom and sides.

Pack the meat mixture into the prepared loaf pan, then cover the top with the remaining bacon slices.

Place the loaf pan in a hot water bath that reaches ¾ up the sides. Bake at 375°F for 20-30 minutes, then reduce heat to 325°F and bake for another 30 minutes.

Remove from oven, place on a wire rack to cool slightly. Cover with aluminum foil and weigh down with about 2 pounds to compress the loaf. Let cool to room temperature, then refrigerate while weighted for 12 hours or overnight.

To serve, slice the meat thinly, warm it, and serve in pita bread with sliced onions, tomatoes, and tzatziki sauce.