In a small skillet, saute the red onion and garlic in the olive oil for about 5-7 minutes until soft.
Defrost the spinach and squeeze out the water.
In a large bowl, mix the ground turkey, spinach, onions and garlic mixture, feta, grill seasoning and oregano. Form into 6 burgers.
Grill burgers until they are completely cooked through.
While burgers are cooking, put the roasted red peppers, parsley and tomato paste into a food processor and process until smooth. Season with salt and pepper.
Place the burgers on the rolls. Top with the roasted red pepper spread and any of the following: sliced tomatoes, sliced cucumbers, sliced red onions, arugula and banana peppers.