How to Make It
In a medium bowl, lightly knead the ground lamb with the onion, garlic, mint, parsley and 1 scant teaspoon each of salt and pepper. Shape the meat into 4 long oval patties about 1/2 inch thick, and transfer them to a plate lined with plastic wrap. Lightly brush the burgers with olive oil.
Light a grill. When the fire is medium hot, brush the grate with olive oil. Grill the lamb burgers for about 12 minutes, turning once, for medium meat. Move the burgers away from the heat and grill the pita until lightly toasted on both sides, about 1 minute.
Set the burgers on the pita breads and top them with the lettuce, tomato, onion and a spoonful of Yogurt-Cucumber Sauce. Fold the pitas over the burgers and serve right away, passing the remaining yogurt sauce alongside.