To prepare the burger, in a medium bowl, gently mix the turkey, salt, parmesan, oregano and garlic. Form into 4 patties, each about 1 inch thick. Spay with olive oil. To cook the burgers, use a non stick griddle pan. Heat very hot. Spray the pan lightly with olive oil. Griddle the burgers for 3-4 minutes on each side until cooked through. To prepare the pita melt, preheat the oven to 350 degrees. Split the pita open and place one turkey burger in each. Top with slices of mango, cheddar cheese and then spread the top side of pita with honey mustard and close the pita sandwich. Spray lightly with olive oil. Place in the oven for 5 minutes until the cheese is melted. Serve immediately with butter lettuce on each pita.