In a medium bowl, combine the ground turkey, garlic powder, onion powder, dried oregano, sea salt, and black pepper until well mixed.
Form the turkey mixture into a single thick patty, ensuring it is even for consistent cooking.
Heat the olive oil in a non-stick skillet over medium-high heat.
Place the patty in the skillet and sear for 5-6 minutes per side, or until the internal temperature reaches 165°F and the exterior is golden brown.
During the last minute of cooking, place the mozzarella cheese on top of the patty and cover the skillet with a lid to melt the cheese.
While the cheese melts, lightly toast the whole grain bun in a separate pan or toaster until crisp.
Warm the marinara sauce in a small saucepan or microwave until heated through.
Assemble the burger by placing the romaine lettuce leaf on the bottom bun, followed by the cheesy turkey patty, and top with the zesty marinara sauce before closing with the top bun.