Place the bell pepper on a dry pan over medium-high heat. Roast until the skin is charred, dark, and flaky, turning occasionally so all sides blister evenly. Set aside to cool, then peel off the skin and finely dice the pepper.
In a large bowl, combine ground beef, diced roasted pepper, grated onion, garlic, paprika, mixed herbs, salt, and black pepper. Mix until well combined.
Cut each pita bread in half to create pockets. Fill each pocket with a portion of the beef mixture, pressing gently so the filling is evenly distributed inside.
Heat a pan over medium heat. Place the stuffed pita open-side down first, so the exposed beef makes direct contact with the pan. Cook until the beef is well seared. Rotate and cook the sides until the pita is golden brown and crisp, and the beef is fully cooked through.
Add jalapeño, Greek yogurt, mayonnaise, cilantro, lemon juice, salt, and black pepper to a blender. Blend until smooth and creamy.
Serve the crispy beef pitas hot with the jalapeño yogurt sauce for dipping.
