Place racks in upper and lower thirds of oven; preheat to 425°. Insert a knife into pocket of each of 4 medium pitas from the side; run knife around circumference to separate into 2 rounds.

Process 1 head of garlic (about 12 cloves), cloves separated, peeled, 2 jalapeños, halved, 1 Tbsp. ground coriander, 1 tsp. ground cumin, ¼ tsp. baking soda, ½ medium white onion, ⅔ cup (packed) parsley leaves with tender stems, 1 Tbsp. paprika, and 4 tsp. Diamond Crystal or 2 tsp. Morton kosher salt in a food processor until finely chopped; transfer to a large bowl. Add 1 lb. ground lamb; mix vigorously with your hands until mixture begins to stick to sides of bowl.

Divide meat mixture among pita (a little over ¼ cup per half). Spread lamb mixture to edges of pitas (it’s easiest if you hold the pita in 1 hand and spread mixture with the other). Arrange on 2 large rimmed baking sheets.

Bake lahmacun, rotating baking sheets top to bottom and front to back halfway through, until meat is cooked and edges of pita are golden, 10–12 minutes. Let cool 2 minutes to allow excess juices to absorb back into meat; transfer to a platter.

Meanwhile, stir ½ cup plain whole-milk Greek or regular yogurt and remaining ½ tsp. Diamond Crystal or ¼ tsp. Morton kosher salt in a small bowl. Sprinkle with a small pinch of paprika.

Serve lahmacun with sliced onion, thinly sliced cabbage, more parsley, seasoned yogurt, and lemon wedges on the side for topping.