Heat the olive oil in a large pot over medium-high heat. Add the bell pepper, onion and a pinch of salt and cook, stirring, until softened, about 7 minutes. Add the garlic, cumin and paprika and cook for another minute. Add the turkey and sprinkle it with 1 1/2 teaspoons salt. Cook, breaking up with a wooden spoon or spatula, until browned all the way through. Add the tomato paste, harissa, brown sugar and tomatoes. Simmer over medium heat for 20 minutes. Stir in the preserved lemon. Taste and adjust the seasoning as desired.
To serve, stack the pitas and wrap in in foil. Heat the oven until warm, a few minutes. Cut the tops off and fill with the turkey mixture. Top with the pickles, feta and parsley.