Preheat your oven to 425°F and line a baking sheet with parchment paper for easy cleanup.
Cut the sweet potato into uniform 1/2-inch thick wedges to ensure even cooking.
In a medium bowl, toss the wedges with olive oil, dried rosemary, and a pinch of sea salt until well coated.
Arrange the fries in a single layer on the baking sheet and roast for 20-25 minutes, flipping halfway through until they are golden and crisp.
While the fries roast, combine the ground turkey, egg white, garlic powder, onion powder, salt, and pepper in a bowl, mixing gently by hand to avoid overworking the meat.
Form the mixture into a single large, thick patty, making a small indentation in the center with your thumb to prevent bulging during cooking.
Heat a high-quality non-stick skillet over medium-high heat and sear the patty for 5-6 minutes per side until the exterior is browned and the internal temperature reaches 165°F.
Assemble the burger by placing the patty inside the romaine lettuce leaves, layering with fresh tomato and red onion slices.
Serve the burger immediately alongside the hot, roasted sweet potato fries for a clean and satisfying meal.