Vegetarian Kofta Pitas

Name: Vegetarian Kofta Pitas
Ingredients: 1 medium onion, cut into chunks; 0.25 cup fresh cilantro leaves; 1.5 (12 ounce) packages meatless ground beef substitute (such as Impossible(TM) Foods); 2 teaspoons ground paprika; 1 teaspoon Greek seasoning; 1 teaspoon ground cumin; 1 teaspoon ground cinnamon; 0.25 teaspoon cayenne pepper; salt and ground black pepper to taste; 4 (6 inch) pita bread rounds, cut in half; 0.5 cup shredded lettuce, or to taste; 0.25 cup diced tomato, or to taste; 2 tablespoons diced onion, or to taste; 8 tablespoons tzatziki