Heat 2 teaspoons of oil in a nonstick skillet over medium-high heat. Add the onion and cook until soft and translucent, about 3 minutes. Add the spinach and cook until wilted, about 1 minute. Remove the pan from the heat. Add the feta cheese, dill and 1/4 teaspoon black pepper and stir to combine.
In bowl, mix ADAMS GREEK SEASONING into ground turkey. Divide the turkey into 4 equal sized rounds. Make 2 equal sized patties out of each round so you have 8 patties total. Put 2 tablespoons of the spinach-feta mixture onto half of the patties. Top with remaining patties working the turkey around the edges to seal burgers closed.
Prepare the grill to medium-high heat. Grill the patties until cooked through, about 5 minutes per side.
To serve, place a burger on the bottom half of each bun, top with about 2 tablespoons of yogurt sauce, then 2 or 3 cucumber slices and a lettuce leaf. Top with the other half of the bun and serve.