For the turkey burgers: Thoroughly combine the turkey, scallions, garlic, paprika, cumin and red pepper flakes in a medium bowl; sprinkle with salt and pepper. Form the mixture into four 3/4-inch-thick patties and season lightly with salt and pepper.
For the feta yogurt sauce: Combine the yogurt, feta, dill, garlic and lemon juice in a small bowl. Season lightly with salt and pepper.
Heat a grill or grill pan over medium-high heat. Toast the English muffins, cut-side down, until golden and set aside. Spray the burgers on both sides with cooking spray and grill until browned and entirely cooked through, 4 to 6 minutes per side. Place each burger on the bottom piece of an English muffin, top with the yogurt sauce and sandwich the top piece of an English muffin.
Recipe courtesy of Bobby Deen