In a medium mixing bowl, combine the feta, onion, garlic, parsley, mint, and spices. Add the turkey and gently mix until all of the ingredients are combined. (I recommend using your hands for this, but a fork will also do if you’re squeamish.)
Gently form the turkey mixture into four patties, approximately ¾-inch thick. Using your thumb, make a small indent in the center of each patty. (This will keep your burgers from puffing up into turkey footballs on the grill.)
Pre-heat a lightly oiled grill (or grill pan) over medium heat.
Meanwhile whip up the harissa yogurt sauce. Combine all the ingredients for the sauce in a small bowl and season with salt to taste. Briefly set aside.
Place the burgers on the hot grill, thumbprint side down, and cook for 5-6 minutes per side until cooked through.
Warm your pitas in the microwave (10-15 seconds should do it) or directly on the grill.
Time to build your burgers! Spread a dollop of yogurt sauce on the bottom half of each pita “bun.” Top each with a small handful of romaine and a burger. Garnish with cucumber, tomato and red onion, and finish with extra yogurt sauce. Sandwich everything together and serve immediately.